diff --git a/.dockerignore b/.dockerignore new file mode 100644 index 0000000..43cb65d --- /dev/null +++ b/.dockerignore @@ -0,0 +1,11 @@ +.git + +.pristine + +.trash + +.recycle + +.backup + +.template diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..e69de29 diff --git a/Dockerfile b/Dockerfile new file mode 100644 index 0000000..d20bdd9 --- /dev/null +++ b/Dockerfile @@ -0,0 +1,15 @@ +FROM titom73/mkdocs AS MKDOCS_BUILD + +RUN pip install markupsafe==2.0.1 + +RUN pip install mkdocs-blog-plugin + +WORKDIR /docs + +COPY . . + +RUN mkdocs build + +FROM mengzyou/bbhttpd:1.35 + +COPY --from=MKDOCS_BUILD --chown=www:www /docs/site /home/www/html diff --git a/Jenkinsfile b/Jenkinsfile new file mode 100644 index 0000000..580599a --- /dev/null +++ b/Jenkinsfile @@ -0,0 +1,56 @@ +pipeline { + + agent none + + options { + + disableConcurrentBuilds(abortPrevious: true) + + buildDiscarder(logRotator(numToKeepStr: '10')) + } + + stages { + + stage('docker compose build') { + + agent { + + label "sian" + + } + + steps { + + dir('.') { + + sh 'docker compose build' + + } + + } + + } + + stage('docker compose push') { + + agent { + + label "sian" + + } + + steps { + + dir('.') { + + sh 'docker compose push' + + } + + } + + } + + } + +} diff --git a/compose.bash b/compose.bash new file mode 100755 index 0000000..b1c7bd0 --- /dev/null +++ b/compose.bash @@ -0,0 +1,19 @@ +#!/bin/bash + +## + +reset + +clear + +## + +set -e + +set -x + +## + +docker compose down --remove-orphans + +docker compose up --build -d diff --git a/compose.yaml b/compose.yaml new file mode 100644 index 0000000..624da44 --- /dev/null +++ b/compose.yaml @@ -0,0 +1,25 @@ +services: + + docker.softwareshinobi.com: + + container_name: docker.softwareshinobi.com + + image: softwareshinobi/docker.softwareshinobi.com + + build: + + context: . + + dockerfile: Dockerfile + + restart: unless-stopped + + ports: + + - 8000:8000 + + volumes: + + - ./docs:/docs/docs + + - ./mkdocs.yml:/docs/mkdocs.yml diff --git a/docs/.Bash-Scripting/000-about-the-author.md b/docs/.Bash-Scripting/000-about-the-author.md new file mode 100755 index 0000000..1882201 --- /dev/null +++ b/docs/.Bash-Scripting/000-about-the-author.md @@ -0,0 +1,91 @@ +# About the book + +* **This version was published on Oct 30 2023** + +This is an open-source introduction to Bash scripting guide that will help you learn the basics of Bash scripting and start writing awesome Bash scripts that will help you automate your daily SysOps, DevOps, and Dev tasks. No matter if you are a DevOps/SysOps engineer, developer, or just a Linux enthusiast, you can use Bash scripts to combine different Linux commands and automate tedious and repetitive daily tasks so that you can focus on more productive and fun things. + +The guide is suitable for anyone working as a developer, system administrator, or a DevOps engineer and wants to learn the basics of Bash scripting. + +The first 13 chapters would be purely focused on getting some solid Bash scripting foundations, then the rest of the chapters would give you some real-life examples and scripts. + +## About the author + +My name is Bobby Iliev, and I have been working as a Linux DevOps Engineer since 2014. I am an avid Linux lover and supporter of the open-source movement philosophy. I am always doing that which I cannot do in order that I may learn how to do it, and I believe in sharing knowledge. + +I think it's essential always to keep professional and surround yourself with good people, work hard, and be nice to everyone. You have to perform at a consistently higher level than others. That's the mark of a true professional. + +For more information, please visit my blog at [https://bobbyiliev.com](https://bobbyiliev.com), follow me on Twitter [@bobbyiliev_](https://twitter.com/bobbyiliev_) and [YouTube](https://www.youtube.com/channel/UCQWmdHTeAO0UvaNqve9udRw). + +## Sponsors + +This book is made possible thanks to these fantastic companies! + +### Materialize + +The Streaming Database for Real-time Analytics. + +[Materialize](https://materialize.com/) is a reactive database that delivers incremental view updates. Materialize helps developers easily build with streaming data using standard SQL. + +### DigitalOcean + +DigitalOcean is a cloud services platform delivering the simplicity developers love and businesses trust to run production applications at scale. + +It provides highly available, secure, and scalable compute, storage, and networking solutions that help developers build great software faster. + +Founded in 2012 with offices in New York and Cambridge, MA, DigitalOcean offers transparent and affordable pricing, an elegant user interface, and one of the largest libraries of open source resources available. + +For more information, please visit [https://www.digitalocean.com](https://www.digitalocean.com) or follow [@digitalocean](https://twitter.com/digitalocean) on Twitter. + +If you are new to DigitalOcean, you can get a free $200 credit and spin up your own servers via this referral link here: + +[Free $200 Credit For DigitalOcean](https://m.do.co/c/2a9bba940f39) + +### DevDojo + +The DevDojo is a resource to learn all things web development and web design. Learn on your lunch break or wake up and enjoy a cup of coffee with us to learn something new. + +Join this developer community, and we can all learn together, build together, and grow together. + +[Join DevDojo](https://devdojo.com?ref=bobbyiliev) + +For more information, please visit [https://www.devdojo.com](https://www.devdojo.com?ref=bobbyiliev) or follow [@thedevdojo](https://twitter.com/thedevdojo) on Twitter. + +## Ebook PDF Generation Tool + +This ebook was generated by [Ibis](https://github.com/themsaid/ibis/) developed by [Mohamed Said](https://github.com/themsaid). + +Ibis is a PHP tool that helps you write eBooks in markdown. + +## Ebook ePub Generation Tool + +The ePub version was generated by [Pandoc](https://pandoc.org/). + +## Book Cover + +The cover for this ebook was created with [Canva.com](https://www.canva.com/join/determined-cork-learn). + +If you ever need to create a graphic, poster, invitation, logo, presentation – or anything that looks good — give Canva a go. + +## License + +MIT License + +Copyright (c) 2020 Bobby Iliev + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/docs/.Bash-Scripting/001-introduction-to-bash.md b/docs/.Bash-Scripting/001-introduction-to-bash.md new file mode 100755 index 0000000..bc2d401 --- /dev/null +++ b/docs/.Bash-Scripting/001-introduction-to-bash.md @@ -0,0 +1,11 @@ +# Introduction to Bash scripting + +Welcome to this Bash basics training guide! In this **bash crash course**, you will learn the **Bash basics** so you could start writing your own Bash scripts and automate your daily tasks. + +Bash is a Unix shell and command language. It is widely available on various operating systems, and it is also the default command interpreter on most Linux systems. + +Bash stands for Bourne-Again SHell. As with other shells, you can use Bash interactively directly in your terminal, and also, you can use Bash like any other programming language to write scripts. This book will help you learn the basics of Bash scripting including Bash Variables, User Input, Comments, Arguments, Arrays, Conditional Expressions, Conditionals, Loops, Functions, Debugging, and testing. + +Bash scripts are great for automating repetitive workloads and can help you save time considerably. For example, imagine working with a group of five developers on a project that requires a tedious environment setup. In order for the program to work correctly, each developer has to manually set up the environment. That's the same and very long task (setting up the environment) repeated five times at least. This is where you and Bash scripts come to the rescue! So instead, you create a simple text file containing all the necessary instructions and share it with your teammates. And now, all they have to do is execute the Bash script and everything will be created for them. + +In order to write Bash scripts, you just need a UNIX terminal and a text editor like Sublime Text, VS Code, or a terminal-based editor like vim or nano. diff --git a/docs/.Bash-Scripting/002-bash-structure.md b/docs/.Bash-Scripting/002-bash-structure.md new file mode 100755 index 0000000..9cc7d59 --- /dev/null +++ b/docs/.Bash-Scripting/002-bash-structure.md @@ -0,0 +1,32 @@ +# Bash Structure + +Let's start by creating a new file with a `.sh` extension. As an example, we could create a file called `devdojo.sh`. + +To create that file, you can use the `touch` command: + +```bash +touch devdojo.sh +``` + +Or you can use your text editor instead: + +```bash +nano devdojo.sh +``` + +In order to execute/run a bash script file with the bash shell interpreter, the first line of a script file must indicate the absolute path to the bash executable: + +```bash +#!/bin/bash +``` + +This is also called a [Shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)). + +All that the shebang does is to instruct the operating system to run the script with the `/bin/bash` executable. + +However, bash is not always in `/bin/bash` directory, particularly on non-Linux systems or due to installation as an optional package. Thus, you may want to use: + +```bash +#!/usr/bin/env bash +``` +It searches for bash executable in directories, listed in PATH environmental variable. diff --git a/docs/.Bash-Scripting/003-bash-hello-world.md b/docs/.Bash-Scripting/003-bash-hello-world.md new file mode 100755 index 0000000..82b8066 --- /dev/null +++ b/docs/.Bash-Scripting/003-bash-hello-world.md @@ -0,0 +1,41 @@ +# Bash Hello World + +Once we have our `devdojo.sh` file created and we've specified the bash shebang on the very first line, we are ready to create our first `Hello World` bash script. + +To do that, open the `devdojo.sh` file again and add the following after the `#!/bin/bash` line: + +```bash +#!/bin/bash + +echo "Hello World!" +``` + +Save the file and exit. + +After that make the script executable by running: + +```bash +chmod +x devdojo.sh +``` + +After that execute the file: + +```bash +./devdojo.sh +``` + +You will see a "Hello World" message on the screen. + +Another way to run the script would be: + +```bash +bash devdojo.sh +``` + +As bash can be used interactively, you could run the following command directly in your terminal and you would get the same result: + +```bash +echo "Hello DevDojo!" +``` + +Putting a script together is useful once you have to combine multiple commands together. diff --git a/docs/.Bash-Scripting/004-bash-variables.md b/docs/.Bash-Scripting/004-bash-variables.md new file mode 100755 index 0000000..df01e3d --- /dev/null +++ b/docs/.Bash-Scripting/004-bash-variables.md @@ -0,0 +1,131 @@ +# Bash Variables + +As in any other programming language, you can use variables in Bash Scripting as well. However, there are no data types, and a variable in Bash can contain numbers as well as characters. + +To assign a value to a variable, all you need to do is use the `=` sign: + +```bash +name="DevDojo" +``` + +>{notice} as an important note, you can not have spaces before and after the `=` sign. + +After that, to access the variable, you have to use the `$` and reference it as shown below: + +```bash +echo $name +``` + +Wrapping the variable name between curly brackets is not required, but is considered a good practice, and I would advise you to use them whenever you can: + +```bash +echo ${name} +``` + +The above code would output: `DevDojo` as this is the value of our `name` variable. + +Next, let's update our `devdojo.sh` script and include a variable in it. + +Again, you can open the file `devdojo.sh` with your favorite text editor, I'm using nano here to open the file: + +```bash +nano devdojo.sh +``` + +Adding our `name` variable here in the file, with a welcome message. Our file now looks like this: + +```bash +#!/bin/bash + +name="DevDojo" + +echo "Hi there $name" +``` + +Save it and run the file using the command below: + +```bash +./devdojo.sh +``` + +You would see the following output on your screen: + +```bash +Hi there DevDojo +``` + +Here is a rundown of the script written in the file: + +* `#!/bin/bash` - At first, we specified our shebang. +* `name=DevDojo` - Then, we defined a variable called `name` and assigned a value to it. +* `echo "Hi there $name"` - Finally, we output the content of the variable on the screen as a welcome message by using `echo` + +You can also add multiple variables in the file as shown below: + +```bash +#!/bin/bash + +name="DevDojo" +greeting="Hello" + +echo "$greeting $name" +``` + +Save the file and run it again: + +```bash +./devdojo.sh +``` + +You would see the following output on your screen: + +```bash +Hello DevDojo +``` +Note that you don't necessarily need to add semicolon `;` at the end of each line. It works both ways, a bit like other programming language such as JavaScript! + + +You can also add variables in the Command Line outside the Bash script and they can be read as parameters: + +```bash +./devdojo.sh Bobby buddy! +``` +This script takes in two parameters `Bobby`and `buddy!` separated by space. In the `devdojo.sh` file we have the following: + +```bash +#!/bin/bash + +echo "Hello there" $1 + +``` +`$1` is the first input (`Bobby`) in the Command Line. Similarly, there could be more inputs and they are all referenced to by the `$` sign and their respective order of input. This means that `buddy!` is referenced to using `$2`. Another useful method for reading variables is the `$@` which reads all inputs. + +So now let's change the `devdojo.sh` file to better understand: + +```bash +#!/bin/bash + +echo "Hello there" $1 + +# $1 : first parameter + +echo "Hello there" $2 + +# $2 : second parameter + +echo "Hello there" $@ + +# $@ : all +``` +The output for: + +```bash +./devdojo.sh Bobby buddy! +``` +Would be the following: + +```bash +Hello there Bobby +Hello there buddy! +Hello there Bobby buddy! +``` diff --git a/docs/.Bash-Scripting/005-bash-user-input.md b/docs/.Bash-Scripting/005-bash-user-input.md new file mode 100755 index 0000000..c0ed6d7 --- /dev/null +++ b/docs/.Bash-Scripting/005-bash-user-input.md @@ -0,0 +1,54 @@ +# Bash User Input + +With the previous script, we defined a variable, and we output the value of the variable on the screen with the `echo $name`. + +Now let's go ahead and ask the user for input instead. To do that again, open the file with your favorite text editor and update the script as follows: + +```bash +#!/bin/bash + +echo "What is your name?" +read name + +echo "Hi there $name" +echo "Welcome to DevDojo!" +``` + +The above will prompt the user for input and then store that input as a string/text in a variable. + +We can then use the variable and print a message back to them. + +The output of the above script would be: + +* First run the script: + +```bash +./devdojo.sh +``` + +* Then, you would be prompted to enter your name: + +``` +What is your name? +Bobby +``` + +* Once you've typed your name, just hit enter, and you will get the following output: + +``` +Hi there Bobby +Welcome to DevDojo! +``` + +To reduce the code, we could change the first `echo` statement with the `read -p`, the `read` command used with `-p` flag will print a message before prompting the user for their input: + +```bash +#!/bin/bash + +read -p "What is your name? " name + +echo "Hi there $name" +echo "Welcome to DevDojo!" +``` + +Make sure to test this out yourself as well! \ No newline at end of file diff --git a/docs/.Bash-Scripting/006-bash-comments.md b/docs/.Bash-Scripting/006-bash-comments.md new file mode 100755 index 0000000..4851007 --- /dev/null +++ b/docs/.Bash-Scripting/006-bash-comments.md @@ -0,0 +1,27 @@ +# Bash Comments + +As with any other programming language, you can add comments to your script. Comments are used to leave yourself notes through your code. + +To do that in Bash, you need to add the `#` symbol at the beginning of the line. Comments will never be rendered on the screen. + +Here is an example of a comment: + +```bash +# This is a comment and will not be rendered on the screen +``` + +Let's go ahead and add some comments to our script: + +```bash +#!/bin/bash + +# Ask the user for their name + +read -p "What is your name? " name + +# Greet the user +echo "Hi there $name" +echo "Welcome to DevDojo!" +``` + +Comments are a great way to describe some of the more complex functionality directly in your scripts so that other people could find their way around your code with ease. \ No newline at end of file diff --git a/docs/.Bash-Scripting/007-bash-arguments.md b/docs/.Bash-Scripting/007-bash-arguments.md new file mode 100755 index 0000000..87fe90c --- /dev/null +++ b/docs/.Bash-Scripting/007-bash-arguments.md @@ -0,0 +1,81 @@ +# Bash Arguments + +You can pass arguments to your shell script when you execute it. To pass an argument, you just need to write it right after the name of your script. For example: + +```bash +./devdojo.com your_argument +``` + +In the script, we can then use `$1` in order to reference the first argument that we specified. + +If we pass a second argument, it would be available as `$2` and so on. + +Let's create a short script called `arguments.sh` as an example: + +```bash +#!/bin/bash + +echo "Argument one is $1" +echo "Argument two is $2" +echo "Argument three is $3" +``` + +Save the file and make it executable: + +```bash +chmod +x arguments.sh +``` + +Then run the file and pass **3** arguments: + +```bash +./arguments.sh dog cat bird +``` + +The output that you would get would be: + +```bash +Argument one is dog +Argument two is cat +Argument three is bird +``` + +To reference all arguments, you can use `$@`: + +```bash +#!/bin/bash + +echo "All arguments: $@" +``` + +If you run the script again: + +```bash +./arguments.sh dog cat bird +``` + +You will get the following output: + +``` +All arguments: dog cat bird +``` + +Another thing that you need to keep in mind is that `$0` is used to reference the script itself. + +This is an excellent way to create self destruct the file if you need to or just get the name of the script. + +For example, let's create a script that prints out the name of the file and deletes the file after that: + +```bash +#!/bin/bash + +echo "The name of the file is: $0 and it is going to be self-deleted." + +rm -f $0 +``` + +You need to be careful with the self deletion and ensure that you have your script backed up before you self-delete it. + + + + diff --git a/docs/.Bash-Scripting/008-bash-arrays.md b/docs/.Bash-Scripting/008-bash-arrays.md new file mode 100755 index 0000000..568bc6d --- /dev/null +++ b/docs/.Bash-Scripting/008-bash-arrays.md @@ -0,0 +1,112 @@ +# Bash Arrays + +If you have ever done any programming, you are probably already familiar with arrays. + +But just in case you are not a developer, the main thing that you need to know is that unlike variables, arrays can hold several values under one name. + +You can initialize an array by assigning values divided by space and enclosed in `()`. Example: + +```bash +my_array=("value 1" "value 2" "value 3" "value 4") +``` + +To access the elements in the array, you need to reference them by their numeric index. + +>{notice} keep in mind that you need to use curly brackets. + +* Access a single element, this would output: `value 2` + +```bash +echo ${my_array[1]} +``` + +* This would return the last element: `value 4` + +```bash +echo ${my_array[-1]} +``` + +* As with command line arguments using `@` will return all arguments in the array, as follows: `value 1 value 2 value 3 value 4` + +```bash +echo ${my_array[@]} +``` + +* Prepending the array with a hash sign (`#`) would output the total number of elements in the array, in our case it is `4`: + +```bash +echo ${#my_array[@]} +``` + +Make sure to test this and practice it at your end with different values. + +## Substring in Bash :: Slicing + +Let's review the following example of slicing in a string in Bash: + +```bash +#!/bin/bash + +letters=( "A""B""C""D""E" ) +echo ${letters[@]} +``` + +This command will print all the elements of an array. + +Output: + +```bash +$ ABCDE +``` + + +Let's see a few more examples: + +- Example 1 + +```bash +#!/bin/bash + +letters=( "A""B""C""D""E" ) +b=${letters:0:2} +echo "${b}" +``` + +This command will print array from starting index 0 to 2 where 2 is exclusive. + +```bash +$ AB +``` + + - Example 2 + +```bash +#!/bin/bash + +letters=( "A""B""C""D""E" ) +b=${letters::5} +echo "${b}" +``` + +This command will print from base index 0 to 5, where 5 is exclusive and starting index is default set to 0 . + +```bash +$ ABCDE +``` + +- Example 3 + +```bash +#!/bin/bash + +letters=( "A""B""C""D""E" ) +b=${letters:3} +echo "${b}" +``` + +This command will print from starting index + 3 to end of array inclusive . + + ```bash + $ DE + ``` diff --git a/docs/.Bash-Scripting/009-bash-conditional-expressions.md b/docs/.Bash-Scripting/009-bash-conditional-expressions.md new file mode 100755 index 0000000..5a96980 --- /dev/null +++ b/docs/.Bash-Scripting/009-bash-conditional-expressions.md @@ -0,0 +1,186 @@ +# Bash Conditional Expressions + +In computer science, conditional statements, conditional expressions, and conditional constructs are features of a programming language, which perform different computations or actions depending on whether a programmer-specified boolean condition evaluates to true or false. + +In Bash, conditional expressions are used by the `[[` compound command and the `[`built-in commands to test file attributes and perform string and arithmetic comparisons. + +Here is a list of the most popular Bash conditional expressions. You do not have to memorize them by heart. You can simply refer back to this list whenever you need it! + +## File expressions + +* True if file exists. + +```bash +[[ -a ${file} ]] +``` + +* True if file exists and is a block special file. + +```bash +[[ -b ${file} ]] +``` + +* True if file exists and is a character special file. + +```bash +[[ -c ${file} ]] +``` + +* True if file exists and is a directory. + +```bash +[[ -d ${file} ]] +``` + +* True if file exists. + +```bash +[[ -e ${file} ]] +``` + +* True if file exists and is a regular file. + +```bash +[[ -f ${file} ]] +``` + +* True if file exists and is a symbolic link. + +```bash +[[ -h ${file} ]] +``` + +* True if file exists and is readable. + +```bash +[[ -r ${file} ]] +``` + +* True if file exists and has a size greater than zero. + +```bash +[[ -s ${file} ]] +``` + +* True if file exists and is writable. + +```bash +[[ -w ${file} ]] +``` + +* True if file exists and is executable. + +```bash +[[ -x ${file} ]] +``` + +* True if file exists and is a symbolic link. + +```bash +[[ -L ${file} ]] +``` + +## String expressions + +* True if the shell variable varname is set (has been assigned a value). + +```bash +[[ -v ${varname} ]] +``` + +True if the length of the string is zero. + +```bash +[[ -z ${string} ]] +``` + +True if the length of the string is non-zero. + +```bash +[[ -n ${string} ]] +``` + +* True if the strings are equal. `=` should be used with the test command for POSIX conformance. When used with the `[[` command, this performs pattern matching as described above (Compound Commands). + +```bash +[[ ${string1} == ${string2} ]] +``` + +* True if the strings are not equal. + +```bash +[[ ${string1} != ${string2} ]] +``` + +* True if string1 sorts before string2 lexicographically. + +```bash +[[ ${string1} < ${string2} ]] +``` + +* True if string1 sorts after string2 lexicographically. + +```bash +[[ ${string1} > ${string2} ]] +``` + +## Arithmetic operators + +* Returns true if the numbers are **equal** + +```bash +[[ ${arg1} -eq ${arg2} ]] +``` + +* Returns true if the numbers are **not equal** + +```bash +[[ ${arg1} -ne ${arg2} ]] +``` + +* Returns true if arg1 is **less than** arg2 + +```bash +[[ ${arg1} -lt ${arg2} ]] +``` + +* Returns true if arg1 is **less than or equal** arg2 + +```bash +[[ ${arg1} -le ${arg2} ]] +``` + +* Returns true if arg1 is **greater than** arg2 + +```bash +[[ ${arg1} -gt ${arg2} ]] +``` + +* Returns true if arg1 is **greater than or equal** arg2 + +```bash +[[ ${arg1} -ge ${arg2} ]] +``` + +As a side note, arg1 and arg2 may be positive or negative integers. + +As with other programming languages you can use `AND` & `OR` conditions: + +```bash +[[ test_case_1 ]] && [[ test_case_2 ]] # And +[[ test_case_1 ]] || [[ test_case_2 ]] # Or +``` + +## Exit status operators + +* returns true if the command was successful without any errors + +```bash +[[ $? -eq 0 ]] +``` + +* returns true if the command was not successful or had errors + +```bash +[[ $? -gt 0 ]] +``` diff --git a/docs/.Bash-Scripting/010-bash-conditionals.md b/docs/.Bash-Scripting/010-bash-conditionals.md new file mode 100755 index 0000000..f6f5e93 --- /dev/null +++ b/docs/.Bash-Scripting/010-bash-conditionals.md @@ -0,0 +1,187 @@ +# Bash Conditionals + +In the last section, we covered some of the most popular conditional expressions. We can now use them with standard conditional statements like `if`, `if-else` and `switch case` statements. + +## If statement + +The format of an `if` statement in Bash is as follows: + +```bash +if [[ some_test ]] +then + +fi +``` + +Here is a quick example which would ask you to enter your name in case that you've left it empty: + +```bash +#!/bin/bash + +# Bash if statement example + +read -p "What is your name? " name + +if [[ -z ${name} ]] +then + echo "Please enter your name!" +fi +``` + +## If Else statement + +With an `if-else` statement, you can specify an action in case that the condition in the `if` statement does not match. We can combine this with the conditional expressions from the previous section as follows: + +```bash +#!/bin/bash + +# Bash if statement example + +read -p "What is your name? " name + +if [[ -z ${name} ]] +then + echo "Please enter your name!" +else + echo "Hi there ${name}" +fi +``` + +You can use the above if statement with all of the conditional expressions from the previous chapters: + +```bash +#!/bin/bash + +admin="devdojo" + +read -p "Enter your username? " username + +# Check if the username provided is the admin + +if [[ "${username}" == "${admin}" ]] ; then + echo "You are the admin user!" +else + echo "You are NOT the admin user!" +fi +``` + +Here is another example of an `if` statement which would check your current `User ID` and would not allow you to run the script as the `root` user: + +```bash +#!/bin/bash + +if (( $EUID == 0 )); then + echo "Please do not run as root" + exit +fi +``` + +If you put this on top of your script it would exit in case that the EUID is 0 and would not execute the rest of the script. This was discussed on [the DigitalOcean community forum](https://www.digitalocean.com/community/questions/how-to-check-if-running-as-root-in-a-bash-script). + +You can also test multiple conditions with an `if` statement. In this example we want to make sure that the user is neither the admin user nor the root user to ensure the script is incapable of causing too much damage. We'll use the `or` operator in this example, noted by `||`. This means that either of the conditions needs to be true. If we used the `and` operator of `&&` then both conditions would need to be true. + +```bash +#!/bin/bash + +admin="devdojo" + +read -p "Enter your username? " username + +# Check if the username provided is the admin + +if [[ "${username}" != "${admin}" ]] || [[ $EUID != 0 ]] ; then + echo "You are not the admin or root user, but please be safe!" +else + echo "You are the admin user! This could be very destructive!" +fi +``` + +If you have multiple conditions and scenarios, then can use `elif` statement with `if` and `else` statements. + +```bash +#!/bin/bash + +read -p "Enter a number: " num + +if [[ $num -gt 0 ]] ; then + echo "The number is positive" +elif [[ $num -lt 0 ]] ; then + echo "The number is negative" +else + echo "The number is 0" +fi +``` + +## Switch case statements + +As in other programming languages, you can use a `case` statement to simplify complex conditionals when there are multiple different choices. So rather than using a few `if`, and `if-else` statements, you could use a single `case` statement. + +The Bash `case` statement syntax looks like this: + +```bash +case $some_variable in + + pattern_1) + commands + ;; + + pattern_2| pattern_3) + commands + ;; + + *) + default commands + ;; +esac +``` + +A quick rundown of the structure: + +* All `case` statements start with the `case` keyword. +* On the same line as the `case` keyword, you need to specify a variable or an expression followed by the `in` keyword. +* After that, you have your `case` patterns, where you need to use `)` to identify the end of the pattern. +* You can specify multiple patterns divided by a pipe: `|`. +* After the pattern, you specify the commands that you would like to be executed in case that the pattern matches the variable or the expression that you've specified. +* All clauses have to be terminated by adding `;;` at the end. +* You can have a default statement by adding a `*` as the pattern. +* To close the `case` statement, use the `esac` (case typed backwards) keyword. + +Here is an example of a Bash `case` statement: + +```bash +#!/bin/bash + +read -p "Enter the name of your car brand: " car + +case $car in + + Tesla) + echo -n "${car}'s car factory is in the USA." + ;; + + BMW | Mercedes | Audi | Porsche) + echo -n "${car}'s car factory is in Germany." + ;; + + Toyota | Mazda | Mitsubishi | Subaru) + echo -n "${car}'s car factory is in Japan." + ;; + + *) + echo -n "${car} is an unknown car brand" + ;; + +esac +``` + +With this script, we are asking the user to input a name of a car brand like Telsa, BMW, Mercedes and etc. + +Then with a `case` statement, we check the brand name and if it matches any of our patterns, and if so, we print out the factory's location. + +If the brand name does not match any of our `case` statements, we print out a default message: `an unknown car brand`. + +## Conclusion + +I would advise you to try and modify the script and play with it a bit so that you could practice what you've just learned in the last two chapters! + +For more examples of Bash `case` statements, make sure to check chapter 16, where we would create an interactive menu in Bash using a `cases` statement to process the user input. diff --git a/docs/.Bash-Scripting/011-bash-loops.md b/docs/.Bash-Scripting/011-bash-loops.md new file mode 100755 index 0000000..37defdd --- /dev/null +++ b/docs/.Bash-Scripting/011-bash-loops.md @@ -0,0 +1,197 @@ +# Bash Loops + +As with any other language, loops are very convenient. With Bash you can use `for` loops, `while` loops, and `until` loops. + +## For loops + +Here is the structure of a for loop: + +```bash +for var in ${list} +do + your_commands +done +``` + +Example: + +```bash +#!/bin/bash + +users="devdojo bobby tony" + +for user in ${users} +do + echo "${user}" +done +``` + +A quick rundown of the example: + +* First, we specify a list of users and store the value in a variable called `$users`. +* After that, we start our `for` loop with the `for` keyword. +* Then we define a new variable which would represent each item from the list that we give. In our case, we define a variable called `user`, which would represent each user from the `$users` variable. +* Then we specify the `in` keyword followed by our list that we will loop through. +* On the next line, we use the `do` keyword, which indicates what we will do for each iteration of the loop. +* Then we specify the commands that we want to run. +* Finally, we close the loop with the `done` keyword. + +You can also use `for` to process a series of numbers. For example here is one way to loop through from 1 to 10: + +```bash +#!/bin/bash + +for num in {1..10} +do + echo ${num} +done +``` + +## While loops + +The structure of a while loop is quite similar to the `for` loop: + +```bash +while [ your_condition ] +do + your_commands +done +``` + +Here is an example of a `while` loop: + +```bash +#!/bin/bash + +counter=1 +while [[ $counter -le 10 ]] +do + echo $counter + ((counter++)) +done +``` + +First, we specified a counter variable and set it to `1`, then inside the loop, we added counter by using this statement here: `((counter++))`. That way, we make sure that the loop will run 10 times only and would not run forever. The loop will complete as soon as the counter becomes 10, as this is what we've set as the condition: `while [[ $counter -le 10 ]]`. + +Let's create a script that asks the user for their name and not allow an empty input: + +```bash +#!/bin/bash + +read -p "What is your name? " name + +while [[ -z ${name} ]] +do + echo "Your name can not be blank. Please enter a valid name!" + read -p "Enter your name again? " name +done + +echo "Hi there ${name}" +``` + +Now, if you run the above and just press enter without providing input, the loop would run again and ask you for your name again and again until you actually provide some input. + +## Until Loops + +The difference between `until` and `while` loops is that the `until` loop will run the commands within the loop until the condition becomes true. + +Structure: + +```bash +until [[ your_condition ]] +do + your_commands +done +``` + +Example: + +```bash +#!/bin/bash + +count=1 +until [[ $count -gt 10 ]] +do + echo $count + ((count++)) +done +``` + +## Continue and Break +As with other languages, you can use `continue` and `break` with your bash scripts as well: + +* `continue` tells your bash script to stop the current iteration of the loop and start the next iteration. + +The syntax of the continue statement is as follows: + +```bash +continue [n] +``` + +The [n] argument is optional and can be greater than or equal to 1. When [n] is given, the n-th enclosing loop is resumed. continue 1 is equivalent to continue. + +```bash +#!/bin/bash + +for i in 1 2 3 4 5 +do + if [[ $i –eq 2 ]] + then + echo "skipping number 2" + continue + fi + echo "i is equal to $i" +done +``` + +We can also use continue command in similar way to break command for controlling multiple loops. + +* `break` tells your bash script to end the loop straight away. + +The syntax of the break statement takes the following form: + +```bash +break [n] +``` +[n] is an optional argument and must be greater than or equal to 1. When [n] is provided, the n-th enclosing loop is exited. break 1 is equivalent to break. + +Example: + +```bash +#!/bin/bash + +num=1 +while [[ $num –lt 10 ]] +do + if [[ $num –eq 5 ]] + then + break + fi + ((num++)) +done +echo "Loop completed" +``` + +We can also use break command with multiple loops. If we want to exit out of current working loop whether inner or outer loop, we simply use break but if we are in inner loop & want to exit out of outer loop, we use break 2. + +Example: + +```bash +#!/bin/bash + +for (( a = 1; a < 10; a++ )) +do + echo "outer loop: $a" + for (( b = 1; b < 100; b++ )) + do + if [[ $b –gt 5 ]] + then + break 2 + fi + echo "Inner loop: $b " + done +done +``` + +The bash script will begin with a=1 & will move to inner loop and when it reaches b=5, it will break the outer loop. +We can use break only instead of break 2, to break inner loop & see how it affects the output. diff --git a/docs/.Bash-Scripting/012-bash-functions.md b/docs/.Bash-Scripting/012-bash-functions.md new file mode 100755 index 0000000..1154962 --- /dev/null +++ b/docs/.Bash-Scripting/012-bash-functions.md @@ -0,0 +1,66 @@ +# Bash Functions + +Functions are a great way to reuse code. The structure of a function in bash is quite similar to most languages: + +```bash +function function_name() { + your_commands +} +``` + +You can also omit the `function` keyword at the beginning, which would also work: + +```bash +function_name() { + your_commands +} +``` + +I prefer putting it there for better readability. But it is a matter of personal preference. + +Example of a "Hello World!" function: + +```bash +#!/bin/bash + +function hello() { + echo "Hello World Function!" +} + +hello +``` + +>{notice} One thing to keep in mind is that you should not add the parenthesis when you call the function. + +Passing arguments to a function work in the same way as passing arguments to a script: + +```bash +#!/bin/bash + +function hello() { + echo "Hello $1!" +} + +hello DevDojo +``` + +Functions should have comments mentioning description, global variables, arguments, outputs, and returned values, if applicable + +```bash +####################################### +# Description: Hello function +# Globals: +# None +# Arguments: +# Single input argument +# Outputs: +# Value of input argument +# Returns: +# 0 if successful, non-zero on error. +####################################### +function hello() { + echo "Hello $1!" +} +``` + +In the next few chapters we will be using functions a lot! diff --git a/docs/.Bash-Scripting/013-debugging-and-testing.md b/docs/.Bash-Scripting/013-debugging-and-testing.md new file mode 100755 index 0000000..06455fc --- /dev/null +++ b/docs/.Bash-Scripting/013-debugging-and-testing.md @@ -0,0 +1,83 @@ +# Debugging, testing and shortcuts + +In order to debug your bash scripts, you can use `-x` when executing your scripts: + +```bash +bash -x ./your_script.sh +``` + +Or you can add `set -x` before the specific line that you want to debug, `set -x` enables a mode of the shell where all executed commands are printed to the terminal. + +Another way to test your scripts is to use this fantastic tool here: + +[https://www.shellcheck.net/](https://www.shellcheck.net/) + +Just copy and paste your code into the textbox, and the tool will give you some suggestions on how you can improve your script. + +You can also run the tool directly in your terminal: + +[https://github.com/koalaman/shellcheck](https://github.com/koalaman/shellcheck) + +If you like the tool, make sure to star it on GitHub and contribute! + +As a SysAdmin/DevOps, I spend a lot of my day in the terminal. Here are my favorite shortcuts that help me do tasks quicker while writing Bash scripts or just while working in the terminal. + +The below two are particularly useful if you have a very long command. + +* Delete everything from the cursor to the end of the line: + +``` +Ctrl + k +``` + +* Delete everything from the cursor to the start of the line: + +``` +Ctrl + u +``` + +* Delete one word backward from cursor: + +``` +Ctrl + w +``` + +* Search your history backward. This is probably the one that I use the most. It is really handy and speeds up my work-flow a lot: + +``` +Ctrl + r +``` + +* Clear the screen, I use this instead of typing the `clear` command: + +``` +Ctrl + l +``` + +* Stops the output to the screen: + +``` +Ctrl + s +``` + +* Enable the output to the screen in case that previously stopped by `Ctrl + s`: + +``` +Ctrl + q +``` + +* Terminate the current command + +``` +Ctrl + c +``` + +* Throw the current command to background: + +``` +Ctrl + z +``` + +I use those regularly every day, and it saves me a lot of time. + +If you think that I've missed any feel free to join the discussion on [the DigitalOcean community forum](https://www.digitalocean.com/community/questions/what-are-your-favorite-bash-shortcuts)! \ No newline at end of file diff --git a/docs/.Bash-Scripting/014-creating-custom-bash-commands.md b/docs/.Bash-Scripting/014-creating-custom-bash-commands.md new file mode 100755 index 0000000..762b713 --- /dev/null +++ b/docs/.Bash-Scripting/014-creating-custom-bash-commands.md @@ -0,0 +1,83 @@ +# Creating custom bash commands + +As a developer or system administrator, you might have to spend a lot of time in your terminal. I always try to look for ways to optimize any repetitive tasks. + +One way to do that is to either write short bash scripts or create custom commands also known as aliases. For example, rather than typing a really long command every time you could just create a shortcut for it. + +## Example + +Let's start with the following scenario, as a system admin, you might have to check the connections to your web server quite often, so I will use the `netstat` command as an example. + +What I would usually do when I access a server that is having issues with the connections to port 80 or 443 is to check if there are any services listening on those ports and the number of connections to the ports. + +The following `netstat` command would show us how many TCP connections on port 80 and 443 we currently have: + +```bash +netstat -plant | grep '80\|443' | grep -v LISTEN | wc -l +``` +This is quite a lengthy command so typing it every time might be time-consuming in the long run especially when you want to get that information quickly. + +To avoid that, we can create an alias, so rather than typing the whole command, we could just type a short command instead. For example, lets say that we wanted to be able to type `conn` (short for connections) and get the same information. All we need to do in this case is to run the following command: + +```bash +alias conn="netstat -plant | grep '80\|443' | grep -v LISTEN | wc -l" +``` + +That way we are creating an alias called `conn` which would essentially be a 'shortcut' for our long `netstat` command. Now if you run just `conn`: + +```bash +conn +``` + +You would get the same output as the long `netstat` command. +You can get even more creative and add some info messages like this one here: + +```bash +alias conn="echo 'Total connections on port 80 and 443:' ; netstat -plant | grep '80\|443' | grep -v LISTEN | wc -l" +``` + +Now if you run `conn` you would get the following output: + +```bash +Total connections on port 80 and 443: +12 +``` +Now if you log out and log back in, your alias would be lost. In the next step you will see how to make this persistent. + +## Making the change persistent + +In order to make the change persistent, we need to add the `alias` command in our shell profile file. + +By default on Ubuntu this would be the `~/.bashrc` file, for other operating systems this might be the `~/.bash_profle`. With your favorite text editor open the file: + +```bash +nano ~/.bashrc +``` + +Go to the bottom and add the following: + +```bash +alias conn="echo 'Total connections on port 80 and 443:' ; netstat -plant | grep '80\|443' | grep -v LISTEN | wc -l" +``` + +Save and then exit. + +That way now even if you log out and log back in again your change would be persisted and you would be able to run your custom bash command. + +## Listing all of the available aliases + +To list all of the available aliases for your current shell, you have to just run the following command: + +```bash +alias +``` + +This would be handy in case that you are seeing some weird behavior with some commands. + +## Conclusion + +This is one way of creating custom bash commands or bash aliases. + +Of course, you could actually write a bash script and add the script inside your `/usr/bin` folder, but this would not work if you don't have root or sudo access, whereas with aliases you can do it without the need of root access. + +>{notice} This was initially posted on [DevDojo.com](https://devdojo.com/bobbyiliev/how-to-create-custom-bash-commands) diff --git a/docs/.Bash-Scripting/015-writing-your-first-bash-script.md b/docs/.Bash-Scripting/015-writing-your-first-bash-script.md new file mode 100755 index 0000000..5077b66 --- /dev/null +++ b/docs/.Bash-Scripting/015-writing-your-first-bash-script.md @@ -0,0 +1,180 @@ +# Write your first Bash script + +Let's try to put together what we've learned so far and create our first Bash script! + +## Planning the script + +As an example, we will write a script that would gather some useful information about our server like: + +* Current Disk usage +* Current CPU usage +* Current RAM usage +* Check the exact Kernel version + +Feel free to adjust the script by adding or removing functionality so that it matches your needs. + +## Writing the script + +The first thing that you need to do is to create a new file with a `.sh` extension. I will create a file called `status.sh` as the script that we will create would give us the status of our server. + +Once you've created the file, open it with your favorite text editor. + +As we've learned in chapter 1, on the very first line of our Bash script we need to specify the so-called [Shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)): + +```bash +#!/bin/bash +``` + +All that the shebang does is to instruct the operating system to run the script with the /bin/bash executable. + +## Adding comments + +Next, as discussed in chapter 6, let's start by adding some comments so that people could easily figure out what the script is used for. To do that right after the shebang you can just add the following: + +```bash +#!/bin/bash + +# Script that returns the current server status +``` + +## Adding your first variable + +Then let's go ahead and apply what we've learned in chapter 4 and add some variables which we might want to use throughout the script. + +To assign a value to a variable in bash, you just have to use the `=` sign. For example, let's store the hostname of our server in a variable so that we could use it later: + +```bash +server_name=$(hostname) +``` + +By using `$()` we tell bash to actually interpret the command and then assign the value to our variable. + +Now if we were to echo out the variable we would see the current hostname: + +```bash +echo $server_name +``` + +## Adding your first function + +As you already know after reading chapter 12, in order to create a function in bash you need to use the following structure: + +```bash +function function_name() { + your_commands +} +``` + +Let's create a function that returns the current memory usage on our server: + +```bash +function memory_check() { + echo "" + echo "The current memory usage on ${server_name} is: " + free -h + echo "" +} +``` + +Quick run down of the function: + +* `function memory_check() {` - this is how we define the function +* `echo ""` - here we just print a new line +* `echo "The current memory usage on ${server_name} is: "` - here we print a small message and the `$server_name` variable +* `}` - finally this is how we close the function + +Then once the function has been defined, in order to call it, just use the name of the function: + +```bash +# Define the function +function memory_check() { + echo "" + echo "The current memory usage on ${server_name} is: " + free -h + echo "" +} + +# Call the function +memory_check +``` + +## Adding more functions challenge + +Before checking out the solution, I would challenge you to use the function from above and write a few functions by yourself. + +The functions should do the following: + +* Current Disk usage +* Current CPU usage +* Current RAM usage +* Check the exact Kernel version + +Feel free to use google if you are not sure what commands you need to use in order to get that information. + +Once you are ready, feel free to scroll down and check how we've done it and compare the results! + +Note that there are multiple correct ways of doing it! + +## The sample script + +Here's what the end result would look like: + +```bash +#!/bin/bash + +## +# BASH script that checks: +# - Memory usage +# - CPU load +# - Number of TCP connections +# - Kernel version +## + +server_name=$(hostname) + +function memory_check() { + echo "" + echo "Memory usage on ${server_name} is: " + free -h + echo "" +} + +function cpu_check() { + echo "" + echo "CPU load on ${server_name} is: " + echo "" + uptime + echo "" +} + +function tcp_check() { + echo "" + echo "TCP connections on ${server_name}: " + echo "" + cat /proc/net/tcp | wc -l + echo "" +} + +function kernel_check() { + echo "" + echo "Kernel version on ${server_name} is: " + echo "" + uname -r + echo "" +} + +function all_checks() { + memory_check + cpu_check + tcp_check + kernel_check +} + +all_checks +``` + +## Conclusion + +Bash scripting is awesome! No matter if you are a DevOps/SysOps engineer, developer, or just a Linux enthusiast, you can use Bash scripts to combine different Linux commands and automate boring and repetitive daily tasks, so that you can focus on more productive and fun things! + +>{notice} This was initially posted on [DevDojo.com](https://devdojo.com/bobbyiliev/introduction-to-bash-scripting) diff --git a/docs/.Bash-Scripting/016-creating-an-interactive-menu-in-bash.md b/docs/.Bash-Scripting/016-creating-an-interactive-menu-in-bash.md new file mode 100755 index 0000000..6666eb5 --- /dev/null +++ b/docs/.Bash-Scripting/016-creating-an-interactive-menu-in-bash.md @@ -0,0 +1,305 @@ +# Creating an interactive menu in Bash + +In this tutorial, I will show you how to create a multiple-choice menu in Bash so that your users could choose between what action should be executed! + +We would reuse some of the code from the previous chapter, so if you have not read it yet make sure to do so. + +## Planning the functionality + +Let's start again by going over the main functionality of the script: + +* Checks the current Disk usage +* Checks the current CPU usage +* Checks the current RAM usage +* Checks the check the exact Kernel version + +In case that you don't have it on hand, here is the script itself: + +```bash +#!/bin/bash + +## +# BASH menu script that checks: +# - Memory usage +# - CPU load +# - Number of TCP connections +# - Kernel version +## + +server_name=$(hostname) + +function memory_check() { + echo "" + echo "Memory usage on ${server_name} is: " + free -h + echo "" +} + +function cpu_check() { + echo "" + echo "CPU load on ${server_name} is: " + echo "" + uptime + echo "" +} + +function tcp_check() { + echo "" + echo "TCP connections on ${server_name}: " + echo "" + cat /proc/net/tcp | wc -l + echo "" +} + +function kernel_check() { + echo "" + echo "Kernel version on ${server_name} is: " + echo "" + uname -r + echo "" +} + +function all_checks() { + memory_check + cpu_check + tcp_check + kernel_check +} +``` + +We will then build a menu that allows the user to choose which function to be executed. + +Of course, you can adjust the function or add new ones depending on your needs. + +## Adding some colors + +In order to make the menu a bit more 'readable' and easy to grasp at first glance, we will add some color functions. + +At the beginning of your script add the following color functions: + +```bash +## +# Color Variables +## +green='\e[32m' +blue='\e[34m' +clear='\e[0m' + +## +# Color Functions +## + +ColorGreen(){ + echo -ne $green$1$clear +} +ColorBlue(){ + echo -ne $blue$1$clear +} +``` + +You can use the color functions as follows: + +```bash +echo -ne $(ColorBlue 'Some text here') +``` + +The above would output the `Some text here` string and it would be blue! + +# Adding the menu + +Finally, to add our menu, we will create a separate function with a case switch for our menu options: + +```bash +menu(){ +echo -ne " +My First Menu +$(ColorGreen '1)') Memory usage +$(ColorGreen '2)') CPU load +$(ColorGreen '3)') Number of TCP connections +$(ColorGreen '4)') Kernel version +$(ColorGreen '5)') Check All +$(ColorGreen '0)') Exit +$(ColorBlue 'Choose an option:') " + read a + case $a in + 1) memory_check ; menu ;; + 2) cpu_check ; menu ;; + 3) tcp_check ; menu ;; + 4) kernel_check ; menu ;; + 5) all_checks ; menu ;; + 0) exit 0 ;; + *) echo -e $red"Wrong option."$clear; WrongCommand;; + esac +} +``` + +### A quick rundown of the code + +First we just echo out the menu options with some color: + +``` +echo -ne " +My First Menu +$(ColorGreen '1)') Memory usage +$(ColorGreen '2)') CPU load +$(ColorGreen '3)') Number of TCP connections +$(ColorGreen '4)') Kernel version +$(ColorGreen '5)') Check All +$(ColorGreen '0)') Exit +$(ColorBlue 'Choose an option:') " +``` + +Then we read the answer of the user and store it in a variable called `$a`: + +```bash + read a +``` + +Finally, we have a switch case which triggers a different function depending on the value of `$a`: + +```bash + case $a in + 1) memory_check ; menu ;; + 2) cpu_check ; menu ;; + 3) tcp_check ; menu ;; + 4) kernel_check ; menu ;; + 5) all_checks ; menu ;; + 0) exit 0 ;; + *) echo -e $red"Wrong option."$clear; WrongCommand;; + esac +``` + +At the end we need to call the menu function to actually print out the menu: + +```bash +# Call the menu function +menu +``` + +## Testing the script + +In the end, your script will look like this: + +```bash +#!/bin/bash + +## +# BASH menu script that checks: +# - Memory usage +# - CPU load +# - Number of TCP connections +# - Kernel version +## + +server_name=$(hostname) + +function memory_check() { + echo "" + echo "Memory usage on ${server_name} is: " + free -h + echo "" +} + +function cpu_check() { + echo "" + echo "CPU load on ${server_name} is: " + echo "" + uptime + echo "" +} + +function tcp_check() { + echo "" + echo "TCP connections on ${server_name}: " + echo "" + cat /proc/net/tcp | wc -l + echo "" +} + +function kernel_check() { + echo "" + echo "Kernel version on ${server_name} is: " + echo "" + uname -r + echo "" +} + +function all_checks() { + memory_check + cpu_check + tcp_check + kernel_check +} + +## +# Color Variables +## +green='\e[32m' +blue='\e[34m' +clear='\e[0m' + +## +# Color Functions +## + +ColorGreen(){ + echo -ne $green$1$clear +} +ColorBlue(){ + echo -ne $blue$1$clear +} + +menu(){ +echo -ne " +My First Menu +$(ColorGreen '1)') Memory usage +$(ColorGreen '2)') CPU load +$(ColorGreen '3)') Number of TCP connections +$(ColorGreen '4)') Kernel version +$(ColorGreen '5)') Check All +$(ColorGreen '0)') Exit +$(ColorBlue 'Choose an option:') " + read a + case $a in + 1) memory_check ; menu ;; + 2) cpu_check ; menu ;; + 3) tcp_check ; menu ;; + 4) kernel_check ; menu ;; + 5) all_checks ; menu ;; + 0) exit 0 ;; + *) echo -e $red"Wrong option."$clear; WrongCommand;; + esac +} + +# Call the menu function +menu +``` + +To test the script, create a new filed with a `.sh` extension, for example: `menu.sh` and then run it: + +```bash +bash menu.sh +``` + +The output that you would get will look like this: + +```bash +My First Menu +1) Memory usage +2) CPU load +3) Number of TCP connections +4) Kernel version +5) Check All +0) Exit +Choose an option: +``` + +You will be able to choose a different option from the list and each number will call a different function from the script: + +![Nice Bash interactive menu](https://imgur.com/8EgxX4m.png) + +## Conclusion + +You now know how to create a Bash menu and implement it in your scripts so that users could select different values! + +>{notice} This content was initially posted on [DevDojo.com](https://devdojo.com/bobbyiliev/how-to-work-with-json-in-bash-using-jq) diff --git a/docs/.Bash-Scripting/017-executing-bash-script-on-multiple-remote-server.md b/docs/.Bash-Scripting/017-executing-bash-script-on-multiple-remote-server.md new file mode 100755 index 0000000..a4f0d47 --- /dev/null +++ b/docs/.Bash-Scripting/017-executing-bash-script-on-multiple-remote-server.md @@ -0,0 +1,129 @@ +# Executing BASH scripts on Multiple Remote Servers + +Any command that you can run from the command line can be used in a bash script. Scripts are used to run a series of commands. Bash is available by default on Linux and macOS operating systems. + +Let's have a hypothetical scenario where you need to execute a BASH script on multiple remote servers, but you don't want to manually copy the script to each server, then again login to each server individually and only then execute the script. + +Of course you could use a tool like Ansible but let's learn how to do that with Bash! + +## Prerequisites + +For this example I will use 3 remote Ubuntu servers deployed on DigitalOcean. If you don't have a Digital Ocean account yet, you can sign up for DigitalOcean and get $100 free credit via this referral link here: + +[https://m.do.co/c/2a9bba940f39](https://m.do.co/c/2a9bba940f39) + +Once you have your Digital Ocean account ready go ahead and deploy 3 droplets. + +I've gone ahead and created 3 Ubuntu servers: + +![DigitalOcean Ubuntu servers](https://imgur.com/09xmq41.png) + +I'll put a those servers IP's in a `servers.txt` file which I would use to loop though with our Bash script. + +If you are new to DigitalOcean you can follow the steps on how to create a Droplet here: + +* [How to Create a Droplet from the DigitalOcean Control Panel](https://www.digitalocean.com/docs/droplets/how-to/create/) + +You can also follow the steps from this video here on how to do your initial server setup: + +* [How to do your Initial Server Setup with Ubuntu](https://youtu.be/7NL2_4HIgKU) + +Or even better, you can follow this article here on how to automate your initial server setup with Bash: + +[Automating Initial Server Setup with Ubuntu 18.04 with Bash](https://www.digitalocean.com/community/tutorials/automating-initial-server-setup-with-ubuntu-18-04) + +With the 3 new servers in place, we can go ahead and focus on running our Bash script on all of them with a single command! + +## The BASH Script + +I will reuse the demo script from the previous chapter with some slight changes. It simply executes a few checks like the current memory usage, the current CPU usage, the number of TCP connections and the version of the kernel. + +```bash +#!/bin/bash + +## +# BASH script that checks the following: +# - Memory usage +# - CPU load +# - Number of TCP connections +# - Kernel version +## + +## +# Memory check +## +server_name=$(hostname) + +function memory_check() { + echo "#######" + echo "The current memory usage on ${server_name} is: " + free -h + echo "#######" +} + + +function cpu_check() { + echo "#######" + echo "The current CPU load on ${server_name} is: " + echo "" + uptime + echo "#######" +} + +function tcp_check() { + echo "#######" + echo "Total TCP connections on ${server_name}: " + echo "" + cat /proc/net/tcp | wc -l + echo "#######" +} + +function kernel_check() { + echo "#######" + echo "The exact Kernel version on ${server_name} is: " + echo "" + uname -r + echo "#######" +} + +function all_checks() { + memory_check + cpu_check + tcp_check + kernel_check +} + +all_checks +``` + +Copy the code bellow and add this in a file called `remote_check.sh`. You can also get the script from [here](https://devdojo.com/bobbyiliev/executing-bash-script-on-multiple-remote-server). + +## Running the Script on all Servers + +Now that we have the script and the servers ready and that we've added those servers in our servers.txt file we can run the following command to loop though all servers and execute the script remotely without having to copy the script to each server and individually connect to each server. + +```bash +for server in $(cat servers.txt) ; do ssh your_user@${server} 'bash -s' < ./remote_check.sh ; done +``` + +What this for loop does is, it goes through each server in the servers.txt file and then it runs the following command for each item in the list: + +```bash +ssh your_user@the_server_ip 'bash -s' < ./remote_check.sh +``` + +You would get the following output: + +![Running bash script on multiple remote servers](https://imgur.com/B1AmhUP.png) + +## Conclusion + +This is just a really simple example on how to execute a simple script on multiple servers without having to copy the script to each server and without having to access the servers individually. + +Of course you could run a much more complex script and on many more servers. + +If you are interested in automation, I would recommend checking out the Ansible resources page on the DigitalOcean website: + +[Ansible Resources](https://www.digitalocean.com/community/tags/ansible) + +>{notice} This content was initially posted on [DevDojo](https://devdojo.com/bobbyiliev/bash-script-to-summarize-your-nginx-and-apache-access-logs) diff --git a/docs/.Bash-Scripting/018-working-with-json-in-bash-using-jq.md b/docs/.Bash-Scripting/018-working-with-json-in-bash-using-jq.md new file mode 100755 index 0000000..8a9e521 --- /dev/null +++ b/docs/.Bash-Scripting/018-working-with-json-in-bash-using-jq.md @@ -0,0 +1,225 @@ +# Work with JSON in BASH using jq + +The `jq` command-line tool is a lightweight and flexible command-line **JSON** processor. It is great for parsing JSON output in BASH. + +One of the great things about `jq` is that it is written in portable C, and it has zero runtime dependencies. All you need to do is to download a single binary or use a package manager like apt and install it with a single command. + +## Planning the script + +For the demo in this tutorial, I would use an external REST API that returns a simple JSON output called the [QuizAPI](https://quizapi.io/): + +> [https://quizapi.io/](https://quizapi.io/) + +If you want to follow along make sure to get a free API key here: + +> [https://quizapi.io/clientarea/settings/token](https://quizapi.io/clientarea/settings/token) + +The QuizAPI is free for developers. + +## Installing jq + +There are many ways to install `jq` on your system. One of the most straight forward ways to do so is to use the package manager depending on your OS. + +Here is a list of the commands that you would need to use depending on your OS: + +* Install jq on Ubuntu/Debian: + +```bash +sudo apt-get install jq +``` + +* Install jq on Fedora: + +```bash +sudo dnf install jq +``` + +* Install jq on openSUSE: + +```bash +sudo zypper install jq +``` + +- Install jq on Arch: + +```bash +sudo pacman -S jq +``` + +* Installing on Mac with Homebrew: + +```bash +brew install jq +``` + +* Install on Mac with MacPort: + +```bash +port install jq +``` + +If you are using other OS, I would recommend taking a look at the official documentation here for more information: + +> [https://stedolan.github.io/jq/download/](https://stedolan.github.io/jq/download/) + +Once you have jq installed you can check your current version by running this command: + +```bash +jq --version +``` + +## Parsing JSON with jq + +Once you have `jq` installed and your QuizAPI API Key, you can parse the JSON output of the QuizAPI directly in your terminal. + +First, create a variable that stores your API Key: + +```bash +API_KEY=YOUR_API_KEY_HERE +``` + +In order to get some output from one of the endpoints of the QuizAPI you can use the curl command: + +```bash +curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" +``` + +For a more specific output, you can use the QuizAPI URL Generator here: + +> [https://quizapi.io/api-config](https://quizapi.io/api-config) + +After running the curl command, the output which you would get would look like this: + +![Raw Json output](https://imgur.com/KghOfzj.png) + +This could be quite hard to read, but thanks to the jq command-line tool, all we need to do is pipe the curl command to jq and we would see a nice formatted JSON output: + +```bash +curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" | jq +``` + +> Note the `| jq` at the end. + +In this case the output that you would get would look something like this: + +![bash jq formatting](https://imgur.com/ebdTtVf.png) + +Now, this looks much nicer! The jq command-line tool formatted the output for us and added some nice coloring! + +## Getting the first element with jq + +Let's say that we only wanted to get the first element from the JSON output, in order to do that we have to just specify the index that we want to see with the following syntax: + +```bash +jq .[0] +``` + +Now, if we run the curl command again and pipe the output to jq .[0] like this: + +```bash +curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" | jq.[0] +``` + +You will only get the first element and the output will look like this: + +![jq get first element only](https://imgur.com/h9bFMAL.png) + +## Getting a value only for specific key + +Sometimes you might want to get only the value of a specific key only, let's say in our example the QuizAPI returns a list of questions along with the answers, description and etc. but what if you wanted to get the Questions only without the additional information? + +This is going to be quite straight forward with `jq`, all you need to do is add the key after jq command, so it would look something like this: + +```bash +jq .[].question +``` + +We have to add the `.[]` as the QuizAPI returns an array and by specifying `.[]` we tell jq that we want to get the .question value for all of the elements in the array. + +The output that you would get would look like this: + +![jq get a value only for specific key](https://imgur.com/0701wHD.png) + +As you can see we now only get the questions without the rest of the values. + +## Using jq in a BASH script + +Let's go ahead and create a small bash script which should output the following information for us: + +* Get only the first question from the output +* Get all of the answers for that question +* Assign the answers to variables +* Print the question and the answers +* To do that I've put together the following script: + +>{notice} make sure to change the API_KEY part with your actual QuizAPI key: + +```bash +#!/bin/bash + +## +# Make an API call to QuizAPI and store the output in a variable +## +output=$(curl 'https://quizapi.io/api/v1/questions?apiKey=API_KEY&limit=10' 2>/dev/null) + +## +# Get only the first question +## +output=$(echo $output | jq .[0]) + +## +# Get the question +## +question=$(echo $output | jq .question) + +## +# Get the answers +## + +answer_a=$(echo $output | jq .answers.answer_a) +answer_b=$(echo $output | jq .answers.answer_b) +answer_c=$(echo $output | jq .answers.answer_c) +answer_d=$(echo $output | jq .answers.answer_d) + +## +# Output the question +## + +echo " +Question: ${question} + +A) ${answer_a} +B) ${answer_b} +C) ${answer_c} +D) ${answer_d} + +" +``` + +If you run the script you would get the following output: + +![Using jq in a bash script](https://imgur.com/LKEsrbq.png) + +We can even go further by making this interactive so that we could actually choose the answer directly in our terminal. + +There is already a bash script that does this by using the QuizAPI and `jq`: + +You can take a look at that script here: + +* [https://github.com/QuizApi/QuizAPI-BASH/blob/master/quiz.sh](https://github.com/QuizApi/QuizAPI-BASH/blob/master/quiz.sh) + +## Conclusion + +The `jq` command-line tool is an amazing tool that gives you the power to work with JSON directly in your BASH terminal. + +That way you can easily interact with all kinds of different REST APIs with BASH. + +For more information, you could take a look at the official documentation here: + +* [https://stedolan.github.io/jq/manual/](https://stedolan.github.io/jq/manual/) + +And for more information on the **QuizAPI**, you could take a look at the official documentation here: + +* [https://quizapi.io/docs/1.0/overview](https://quizapi.io/docs/1.0/overview) + +>{notice} This content was initially posted on [DevDojo.com](https://devdojo.com/bobbyiliev/how-to-work-with-json-in-bash-using-jq) diff --git a/docs/.Bash-Scripting/019-working-with-cloudflare-api-with-bash.md b/docs/.Bash-Scripting/019-working-with-cloudflare-api-with-bash.md new file mode 100755 index 0000000..9b66ad3 --- /dev/null +++ b/docs/.Bash-Scripting/019-working-with-cloudflare-api-with-bash.md @@ -0,0 +1,104 @@ +# Working with Cloudflare API with Bash + +I host all of my websites on **DigitalOcean** Droplets and I also use Cloudflare as my CDN provider. One of the benefits of using Cloudflare is that it reduces the overall traffic to your user and also hides your actual server IP address behind their CDN. + +My personal favorite Cloudflare feature is their free DDoS protection. It has saved my servers multiple times from different DDoS attacks. They have a cool API that you could use to enable and disable their DDoS protection easily. + +This chapter is going to be an exercise! I challenge you to go ahead and write a short bash script that would enable and disable the Cloudflare DDoS protection for your server automatically if needed! + +## Prerequisites + +Before following this guide here, please set up your Cloudflare account and get your website ready. If you are not sure how to do that you can follow these steps here: [Create a Cloudflare account and add a website](https://support.cloudflare.com/hc/en-us/articles/201720164-Step-2-Create-a-Cloudflare-account-and-add-a-website). + +Once you have your Cloudflare account, make sure to obtain the following information: + +* A Cloudflare account +* Cloudflare API key +* Cloudflare Zone ID + +Also, Make sure curl is installed on your server: + +```bash +curl --version +``` + +If curl is not installed you need to run the following: + +* For RedHat/CentOs: + +```bash +yum install curl +``` + +* For Debian/Ubuntu + +```bash +apt-get install curl +``` + +## Challenge - Script requirements + +The script needs to monitor the CPU usage on your server and if the CPU usage gets high based on the number vCPU it would enable the Cloudflare DDoS protection automatically via the Cloudflare API. + +The main features of the script should be: + +* Checks the script CPU load on the server +* In case of a CPU spike the script triggers an API call to Cloudflare and enables the DDoS protection feature for the specified zone +* After the CPU load is back to normal the script would disable the "I'm under attack" option and set it back to normal + +## Example script + +I already have prepared a demo script which you could use as a reference. But I encourage you to try and write the script yourself first and only then take a look at my script! + +To download the script just run the following command: + +```bash +wget https://raw.githubusercontent.com/bobbyiliev/cloudflare-ddos-protection/main/protection.sh +``` + +Open the script with your favorite text editor: + +```bash +nano protection.sh +``` + +And update the following details with your Cloudflare details: + +```bash +CF_CONE_ID=YOUR_CF_ZONE_ID +CF_EMAIL_ADDRESS=YOUR_CF_EMAIL_ADDRESS +CF_API_KEY=YOUR_CF_API_KEY +``` + +After that make the script executable: + +```bash +chmod +x ~/protection.sh +``` + +Finally, set up 2 Cron jobs to run every 30 seconds. To edit your crontab run: + +```bash +crontab -e +``` + +And add the following content: + +```bash +* * * * * /path-to-the-script/cloudflare/protection.sh +* * * * * ( sleep 30 ; /path-to-the-script/cloudflare/protection.sh ) +``` + +Note that you need to change the path to the script with the actual path where you've stored the script at. + +## Conclusion + +This is quite straight forward and budget solution, one of the downsides of the script is that if your server gets unresponsive due to an attack, the script might not be triggered at all. + +Of course, a better approach would be to use a monitoring system like Nagios and based on the statistics from the monitoring system then you can trigger the script, but this script challenge could be a good learning experience! + +Here is another great resource on how to use the Discord API and send notifications to your Discord Channel with a Bash script: + +[How To Use Discord Webhooks to Get Notifications for Your Website Status on Ubuntu 18.04](https://www.digitalocean.com/community/tutorials/how-to-use-discord-webhooks-to-get-notifications-for-your-website-status-on-ubuntu-18-04) + +>{notice} This content was initially posted on [DevDojo](https://devdojo.com/bobbyiliev/bash-script-to-automatically-enable-cloudflare-ddos-protection) diff --git a/docs/.Bash-Scripting/020-nginx-and-apache-log-parser.md b/docs/.Bash-Scripting/020-nginx-and-apache-log-parser.md new file mode 100755 index 0000000..22bc5ec --- /dev/null +++ b/docs/.Bash-Scripting/020-nginx-and-apache-log-parser.md @@ -0,0 +1,83 @@ +# BASH Script parser to Summarize Your NGINX and Apache Access Logs + +One of the first things that I would usually do in case I notice a high CPU usage on some of my Linux servers would be to check the process list with either top or htop and in case that I notice a lot of Apache or Nginx process I would quickly check my access logs to determine what has caused or is causing the CPU spike on my server or to figure out if anything malicious is going on. + +Sometimes reading the logs could be quite intimidating as the log might be huge and going though it manually could take a lot of time. Also, the raw log format could be confusing for people with less experience. + +Just like the previous chapter, this chapter is going to be a challenge! You need to write a short bash script that would summarize the whole access log for you without the need of installing any additional software. + +# Script requirements + +This BASH script needs to parse and summarize your access logs and provide you with very useful information like: + +* The 20 top pages with the most POST requests +* The 20 top pages with the most GET requests +* Top 20 IP addresses and their geo-location + +## Example script + +I already have prepared a demo script which you could use as a reference. But I encourage you to try and write the script yourself first and only then take a look at my script! + +In order to download the script, you can either clone the repository with the following command: + +```bash +git clone https://github.com/bobbyiliev/quick_access_logs_summary.git +``` + +Or run the following command which would download the script in your current directory: + +```bash +wget https://raw.githubusercontent.com/bobbyiliev/quick_access_logs_summary/master/spike_check +``` + +The script does not make any changes to your system, it only reads the content of your access log and summarizes it for you, however, once you've downloaded the file, make sure to review the content yourself. + +## Running the script + +All that you have to do once the script has been downloaded is to make it executable and run it. + +To do that run the following command to make the script executable: + +```bash +chmod +x spike_check +``` + +Then run the script: + +```bash +./spike_check /path/to/your/access_log +``` + +Make sure to change the path to the file with the actual path to your access log. For example if you are using Apache on an Ubuntu server, the exact command would look like this: + +```bash +./spike_check /var/log/apache2/access.log +``` + +If you are using Nginx the exact command would be almost the same, but with the path to the Nginx access log: + +```bash +./spike_check /var/log/nginx/access.log +``` + +## Understanding the output + +Once you run the script, it might take a while depending on the size of the log. + +The output that you would see should look like this: + +![Summarized access log](https://imgur.com/WWHVMrj.png) + +Essentially what we can tell in this case is that we've received 16 POST requests to our xmlrpc.php file which is often used by attackers to try and exploit WordPress websites by using various username and password combinations. + +In this specific case, this was not a huge brute force attack, but it gives us an early indication and we can take action to prevent a larger attack in the future. + +We can also see that there were a couple of Russian IP addresses accessing our site, so in case that you do not expect any traffic from Russia, you might want to block those IP addresses as well. + +## Conclusion + +This is an example of a simple BASH script that allows you to quickly summarize your access logs and determine if anything malicious is going on. + +Of course, you might want to also manually go through the logs as well but it is a good challenge to try and automate this with Bash! + +>{notice} This content was initially posted on [DevDojo](https://devdojo.com/bobbyiliev/bash-script-to-summarize-your-nginx-and-apache-access-logs) diff --git a/docs/.Bash-Scripting/021-how-to-send-emails-with-bash.md b/docs/.Bash-Scripting/021-how-to-send-emails-with-bash.md new file mode 100755 index 0000000..bce8624 --- /dev/null +++ b/docs/.Bash-Scripting/021-how-to-send-emails-with-bash.md @@ -0,0 +1,95 @@ +# Sending emails with Bash and SSMTP + +SSMTP is a tool that delivers emails from a computer or a server to a configured mail host. + +SSMTP is not an email server itself and does not receive emails or manage a queue. + +One of its primary uses is for forwarding automated email (like system alerts) off your machine and to an external email address. + +## Prerequisites + +You would need the following things in order to be able to complete this tutorial successfully: + +* Access to an Ubuntu 18.04 server as a non-root user with sudo privileges and an active firewall installed on your server. To set these up, please refer to our [Initial Server Setup Guide for Ubuntu 18.04](https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-18-04) + +* An SMTP server along with SMTP username and password, this would also work with Gmail's SMTP server, or you could set up your own SMTP server by following the steps from this tutorial on [How to Install and Configure Postfix as a Send-Only SMTP Server on Ubuntu 16.04](https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-16-04) + +## Installing SSMTP + +In order to install SSMTP, you’ll need to first update your apt cache with: + +```bash +sudo apt update +``` + +Then run the following command to install SSMTP: + +```bash +sudo apt install ssmtp +``` + +Another thing that you would need to install is `mailutils`, to do that run the following command: + +```bash +sudo apt install mailutils +``` + +## Configuring SSMTP + +Now that you have `ssmtp` installed, in order to configure it to use your SMTP server when sending emails, you need to edit the SSMTP configuration file. + +Using your favourite text editor to open the `/etc/ssmtp/ssmtp.conf` file: + +```bash +sudo nano /etc/ssmtp/ssmtp.conf +``` + +You need to include your SMTP configuration: + +``` +root=postmaster +mailhub=<^>your_smtp_host.com<^>:587 +hostname=<^>your_hostname<^> +AuthUser=<^>your_gmail_username@your_smtp_host.com<^> +AuthPass=<^>your_gmail_password<^> +FromLineOverride=YES +UseSTARTTLS=YES +``` + +Save the file and exit. + +## Sending emails with SSMTP + +Once your configuration is done, in order to send an email just run the following command: + +```bash +echo "<^>Here add your email body<^>" | mail -s "<^>Here specify your email subject<^>" <^>your_recepient_email@yourdomain.com<^> +``` + +You can run this directly in your terminal or include it in your bash scripts. + +## Sending A File with SSMTP (optional) + +If you need to send files as attachments, you can use `mpack`. + +To install `mpack` run the following command: + +```bash +sudo apt install mpack +``` + +Next, in order to send an email with a file attached, run the following command. + +```bash +mpack -s "<^>Your Subject here<^>" your_file.zip <^>your_recepient_email@yourdomain.com<^> +``` + +The above command would send an email to `<^>your_recepient_email@yourdomain.com<^>` with the `<^>your_file.zip<^>` attached. + +## Conclusion + +SSMTP is a great and reliable way to implement SMTP email functionality directly in bash scripts. + +For more information about SSMTP I would recommend checking the official documentation [here](https://wiki.archlinux.org/index.php/SSMTP). + +>{notice} This content was initially posted on the [DigitalOcean community forum](https://www.digitalocean.com/community/questions/how-to-send-emails-from-a-bash-script-using-ssmtp). diff --git a/docs/.Bash-Scripting/022-bash-password-generator.md b/docs/.Bash-Scripting/022-bash-password-generator.md new file mode 100755 index 0000000..d9d9170 --- /dev/null +++ b/docs/.Bash-Scripting/022-bash-password-generator.md @@ -0,0 +1,126 @@ +# Password Generator Bash Script + +It's not uncommon situation where you will need to generate a random password that you can use for any software installation or when you sign-up to any website. + +There are a lot of options in order to achieve this. You can use a password manager/vault where you often have the option to randomly generate a password or to use a website that can generate the password on your behalf. + +You can also use Bash in your terminal (command-line) to generate a password that you can quickly use. There are a lot of ways to achieve that and I will make sure to cover few of them and will leave up to you to choose which option is most suitable with your needs. + +## :warning: Security + +**This script is intended to practice your bash scripting skills. You can have fun while doing simple projects with BASH, but security is not a joke, so please make sure you do not save your passwords in plain text in a local file or write them down by hand on a piece of paper.** + +**I will highly recommend everyone to use secure and trusted providers to generate and save the passwords.** + +## Script summary + +Let me first do a quick summary of what our script is going to do.: + +1. We will have to option to choose the password characters length when the script is executed. +2. The script will then generate 5 random passwords with the length that was specified in step 1 + +## Prerequisites + +You would need a bash terminal and a text editor. You can use any text editor like vi, vim, nano or Visual Studio Code. + +I'm running the script locally on my Linux laptop but if you're using Windows PC you can ssh to any server of your choice and execute the script there. + +Although the script is pretty simple, having some basic BASH scripting knowledge will help you to better understand the script and how it's working. + +## Generate a random password +One of the great benefits of Linux is that you can do a lot of things using different methods. When it comes to generating a random string of characters it's not different as well. + +You can use several commands in order to generate a random string of characters. I will cover few of them and will provide some examples. + +- Using the ```date``` command. +The date command will output the current date and time. However we also further manipulate the output in order to use it as randomly generated password. We can hash the date using md5, sha or just run it through base64. These are few examples: + +``` +date | md5sum +94cb1cdecfed0699e2d98acd9a7b8f6d - +``` +using sha256sum: + +``` +date | sha256sum +30a0c6091e194c8c7785f0d7bb6e1eac9b76c0528f02213d1b6a5fbcc76ceff4 - +``` +using base64: +``` +date | base64 +0YHQsSDRj9C90YMgMzAgMTk6NTE6NDggRUVUIDIwMjEK +``` + +- We can also use openssl in order to generate pseudo-random bytes and run the output through base64. An example output will be: +``` +openssl rand -base64 10 +9+soM9bt8mhdcw== +``` +Keep in mind that openssl might not be installed on your system so it's likely that you will need to install it first in order to use it. + +- The most preferred way is to use the pseudorandom number generator - /dev/urandom +since it is intended for most cryptographic purposes. We would also need to manipulate the output using ```tr``` in order to translate it. An example command is: + +``` +tr -cd '[:alnum:]' < /dev/urandom | fold -w10 | head -n 1 +``` +With this command we take the output from /dev/urandom and translate it with ```tr``` while using all letters and digits and print the desired number of characters. + +## The script +First we begin the script with the shebang. We use it to tell the operating system which interpreter to use to parse the rest of the file. +``` +#!/bin/bash +``` +We can then continue and ask the user for some input. In this case we would like to know how many characters the password needs to be: + +``` +# Ask user for password length +clear +printf "\n" +read -p "How many characters you would like the password to have? " pass_length +printf "\n" +``` +Generate the passwords and then print it so the user can use it. +``` +# This is where the magic happens! +# Generate a list of 10 strings and cut it to the desired value provided from the user + +for i in {1..10}; do (tr -cd '[:alnum:]' < /dev/urandom | fold -w${pass_length} | head -n 1); done + +# Print the strings +printf "$pass_output\n" +printf "Goodbye, ${USER}\n" +``` + +## The full script: +``` +#!/bin/bash +#======================================= +# Password generator with login option +#======================================= + +# Ask user for the string length +clear +printf "\n" +read -p "How many characters you would like the password to have? " pass_length +printf "\n" + +# This is where the magic happens! +# Generate a list of 10 strings and cut it to the desired value provided from the user + +for i in {1..10}; do (tr -cd '[:alnum:]' < /dev/urandom | fold -w${pass_length} | head -n 1); done + +# Print the strings +printf "$pass_output\n" +printf "Goodbye, ${USER}\n" +``` + +## Conclusion +This is pretty much how you can use simple bash script to generate random passwords. + +:warning: **As already mentioned, please make sure to use strong passwords in order to make sure your account is protected. Also whenever is possible use 2 factor authentication as this will provide additional layer of security for your account.** + +While the script is working fine, it expects that the user will provide the requested input. In order to prevent any issues you would need to do some more advance checks on the user input in order to make sure the script will continue to work fine even if the provided input does not match our needs. + +## Contributed by +[Alex Georgiev](https://twitter.com/alexgeorgiev17) diff --git a/docs/.Bash-Scripting/023-bash-redirection.md b/docs/.Bash-Scripting/023-bash-redirection.md new file mode 100755 index 0000000..7339e26 --- /dev/null +++ b/docs/.Bash-Scripting/023-bash-redirection.md @@ -0,0 +1,228 @@ +# Redirection in Bash + +A Linux superuser must have a good knowledge of pipes and redirection in Bash. It is an essential component of the system and is often helpful in the field of Linux System Administration. + +When you run a command like ``ls``, ``cat``, etc, you get some output on the terminal. If you write a wrong command, pass a wrong flag or a wrong command-line argument, you get error output on the terminal. +In both the cases, you are given some text. It may seem like "just text" to you, but the system treats this text differently. This identifier is known as a File Descriptor (fd). + +In Linux, there are 3 File Descriptors, **STDIN** (0); **STDOUT** (1) and **STDERR** (2). + +* **STDIN** (fd: 0): Manages the input in the terminal. +* **STDOUT** (fd: 1): Manages the output text in the terminal. +* **STDERR** (fd: 2): Manages the error text in the terminal. + +# Difference between Pipes and Redirections + +Both *pipes* and *redidertions* redirect streams `(file descriptor)` of process being executed. The main difference is that *redirections* deal with `files stream`, sending the output stream to a file or sending the content of a given file to the input stream of the process. + +On the other hand a pipe connects two commands by sending the output stream of the first one to the input stream of the second one. without any redidertions specified. + +# Redirection in Bash + +## STDIN (Standard Input) +When you enter some input text for a command that asks for it, you are actually entering the text to the **STDIN** file descriptor. Run the ``cat`` command without any command-line arguments. +It may seem that the process has paused but in fact it's ``cat`` asking for **STDIN**. ``cat`` is a simple program and will print the text passed to **STDIN**. However, you can extend the use case by redirecting the input to the commands that take **STDIN**. + +Example with ``cat``: +``` +cat << EOF +Hello World! +How are you? +EOF +``` +This will simply print the provided text on the terminal screen: +``` +Hello World! +How are you? +``` + +The same can be done with other commands that take input via STDIN. Like, ``wc``: +``` +wc -l << EOF +Hello World! +How are you? +EOF +``` +The ``-l`` flag with ``wc`` counts the number of lines. +This block of bash code will print the number of lines to the terminal screen: +``` +2 +``` + +## STDOUT (Standard Output) +The normal non-error text on your terminal screen is printed via the **STDOUT** file descriptor. The **STDOUT** of a command can be redirected into a file, in such a way that the output of the command is written to a file instead of being printed on the terminal screen. +This is done simply with the help of ``>`` and ``>>`` operators. + +Example: +``` +echo "Hello World!" > file.txt +``` +The above command will not print "Hello World" on the terminal screen, it will instead create a file called ``file.txt`` and will write the "Hello World" string to it. +This can be verified by running the ``cat`` command on the ``file.txt`` file. +``` +cat file.txt +``` + +However, everytime you redirect the **STDOUT** of any command multiple times to the same file, it will remove the existing contents of the file to write the new ones. + +Example: +``` +echo "Hello World!" > file.txt +echo "How are you?" > file.txt +``` + +On running ``cat`` on ``file.txt`` file: +``` +cat file.txt +``` + +You will only get the "How are you?" string printed. +``` +How are you? +``` + +This is because the "Hello World" string has been overwritten. +This behaviour can be avoided using the ``>>`` operator. + +The above example can be written as: +``` +echo "Hello World!" > file.txt +echo "How are you?" >> file.txt +``` + +On running ``cat`` on the ``file.txt`` file, you will get the desired result. +``` +Hello World! +How are you? +``` + +Alternatively, the redirection operator for **STDOUT** can also be written as ``1>``. Like, +``` +echo "Hello World!" 1> file.txt +``` + +## STDERR (Standard Error) + +The error text on the terminal screen is printed via the **STDERR** of the command. For example: +``` +ls --hello +``` +would give an error messages. This error message is the **STDERR** of the command. + +**STDERR** can be redirected using the ``2>`` operator. + +``` +ls --hello 2> error.txt +``` + +This command will redirect the error message to the ``error.txt`` file and write it to it. This can be verified by running the ``cat`` command on the ``error.txt`` file. + +You can also use the ``2>>`` operator for **STDERR** just like you used ``>>`` for **STDOUT**. + +Error messages in Bash Scripts can be undesirable sometimes. You can choose to ignore them by redirecting the error message to the ``/dev/null`` file. +``/dev/null`` is pseudo-device that takes in text and then immediately discards it. + +The above example can be written follows to ignore the error text completely: +``` +ls --hello 2> /dev/null +``` + +Of course, you can redirect both **STDOUT** and **STDERR** for the same command or script. +``` +./install_package.sh > output.txt 2> error.txt +``` + +Both of them can be redirected to the same file as well. +``` +./install_package.sh > file.txt 2> file.txt +``` + +There is also a shorter way to do this. +``` +./install_package.sh > file.txt 2>&1 +``` + +# Piping + +So far we have seen how to redirect the **STDOUT**, **STDIN** and **STDOUT** to and from a file. +To concatenate the output of program *(command)* as the input of another program *(command)* you can use a vertical bar `|`. + +Example: +``` +ls | grep ".txt" +``` +This command will list the files in the current directory and pass output to *`grep`* command which then filter the output to only show the files that contain the string ".txt". + +Syntax: +``` +[time [-p]] [!] command1 [ | or |& command2 ] … +``` + +You can also build arbitrary chains of commands by piping them together to achieve a powerful result. + +This example creates a listing of every user which owns a file in a given directory as well as how many files and directories they own: +``` +ls -l /projects/bash_scripts | tail -n +2 | sed 's/\s\s*/ /g' | cut -d ' ' -f 3 | sort | uniq -c +``` +Output: +``` +8 anne +34 harry +37 tina +18 ryan +``` + +# HereDocument + +The symbol `<<` can be used to create a temporary file [heredoc] and redirect from it at the command line. +``` +COMMAND << EOF + ContentOfDocument + ... + ... +EOF +``` +Note here that `EOF` represents the delimiter (end of file) of the heredoc. In fact, we can use any alphanumeric word in its place to signify the start and the end of the file. For instance, this is a valid heredoc: +``` +cat << randomword1 + This script will print these lines on the terminal. + Note that cat can read from standard input. Using this heredoc, we can + create a temporary file with these lines as it's content and pipe that + into cat. +randomword1 +``` + +Effectively it will appear as if the contents of the heredoc are piped into the command. This can make the script very clean if multiple lines need to be piped into a program. + +Further, we can attach more pipes as shown: +``` +cat << randomword1 | wc + This script will print these lines on the terminal. + Note that cat can read from standard input. Using this heredoc, we can + create a temporary file with these lines as it's content and pipe that + into cat. +randomword1 +``` + +Also, pre-defined variables can be used inside the heredocs. + +# HereString + +Herestrings are quite similar to heredocs but use `<<<`. These are used for single line strings that have to be piped into some program. This looks cleaner that heredocs as we don't have to specify the delimiter. + +``` +wc <<<"this is an easy way of passing strings to the stdin of a program (here wc)" +``` + +Just like heredocs, herestrings can contain variables. + +## Summary +|**Operator** |**Description** | +|:---|:---| +|`>`|`Save output to a file`| +|`>>`|`Append output to a file`| +|`<`|`Read input from a file`| +|`2>`|`Redirect error messages`| +|`\|`|`Send the output from one program as input to another program`| +|`<<`|`Pipe multiple lines into a program cleanly`| +|`<<<`|`Pipe a single line into a program cleanly`| diff --git a/docs/.Bash-Scripting/024-automating-wordpress-lamp-with-bash.md b/docs/.Bash-Scripting/024-automating-wordpress-lamp-with-bash.md new file mode 100755 index 0000000..d7ca9eb --- /dev/null +++ b/docs/.Bash-Scripting/024-automating-wordpress-lamp-with-bash.md @@ -0,0 +1,336 @@ +# Automatic WordPress on LAMP installation with BASH + +Here is an example of a full LAMP and WordPress installation that works on any Debian-based machine. + +# Prerequisites + +- A Debian-based machine (Ubuntu, Debian, Linux Mint, etc.) + +# Planning the functionality + +Let's start again by going over the main functionality of the script: + +**Lamp Installation** + +* Update the package manager +* Install a firewall (ufw) +* Allow SSH, HTTP and HTTPS traffic +* Install Apache2 +* Install & Configure MariaDB +* Install PHP and required plugins +* Enable all required Apache2 mods + +**Apache Virtual Host Setup** + +* Create a directory in `/var/www` +* Configure permissions to the directory +* Create the `$domain` file under `/etc/apache2/sites-available` and append the required Virtualhost content +* Enable the site +* Restart Apache2 + +**SSL Config** + +* Generate the OpenSSL certificate +* Append the SSL certificate to the `ssl-params.conf` file +* Append the SSL config to the Virtualhost file +* Enable SSL +* Reload Apache2 + +**Database Config** + +* Create a database +* Create a user +* Flush Privileges + +**WordPress Config** + +* Install required WordPress PHP plugins +* Install WordPress +* Append the required information to `wp-config.php` file + +Without further ado, let's start writing the script. + +# The script + +We start by setting our variables and asking the user to input their domain: + +```bash +echo 'Please enter your domain of preference without www:' +read DOMAIN +echo "Please enter your Database username:" +read DBUSERNAME +echo "Please enter your Database password:" +read DBPASSWORD +echo "Please enter your Database name:" +read DBNAME + +ip=`hostname -I | cut -f1 -d' '` +``` + +We are now ready to start writing our functions. Start by creating the `lamp_install()` function. Inside of it, we are going to update the system, install ufw, allow SSH, HTTP and HTTPS traffic, install Apache2, install MariaDB and PHP. We are also going to enable all required Apache2 mods. + +```bash +lamp_install () { + apt update -y + apt install ufw + ufw enable + ufw allow OpenSSH + ufw allow in "WWW Full" + + apt install apache2 -y + apt install mariadb-server + mysql_secure_installation -y + apt install php libapache2-mod-php php-mysql -y + sed -i "2d" /etc/apache2/mods-enabled/dir.conf + sed -i "2i\\\tDirectoryIndex index.php index.html index.cgi index.pl index.xhtml index.htm" /etc/apache2/mods-enabled/dir.conf + systemctl reload apache2 + +} +``` + +Next, we are going to create the `apache_virtualhost_setup()` function. Inside of it, we are going to create a directory in `/var/www`, configure permissions to the directory, create the `$domain` file under `/etc/apache2/sites-available` and append the required Virtualhost content, enable the site and restart Apache2. + +```bash +apache_virtual_host_setup () { + mkdir /var/www/$DOMAIN + chown -R $USER:$USER /var/www/$DOMAIN + + echo "" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerName $DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerAlias www.$DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerAdmin webmaster@localhost" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tDocumentRoot /var/www/$DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e '\tErrorLog ${APACHE_LOG_DIR}/error.log' >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e '\tCustomLog ${APACHE_LOG_DIR}/access.log combined' >> /etc/apache2/sites-available/$DOMAIN.conf + echo "" >> /etc/apache2/sites-available/$DOMAIN.conf + a2ensite $DOMAIN + a2dissite 000-default + systemctl reload apache2 + +} +``` + +Next, we are going to create the `ssl_config()` function. Inside of it, we are going to generate the OpenSSL certificate, append the SSL certificate to the `ssl-params.conf` file, append the SSL config to the Virtualhost file, enable SSL and reload Apache2. + +```bash +ssl_config () { + openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/private/apache-selfsigned.key -out /etc/ssl/certs/apache-selfsigned.crt + + echo "SSLCipherSuite EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLProtocol All -SSLv2 -SSLv3 -TLSv1 -TLSv1.1" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLHonorCipherOrder On" >> /etc/apache2/conf-available/ssl-params.conf + echo "Header always set X-Frame-Options DENY" >> /etc/apache2/conf-available/ssl-params.conf + echo "Header always set X-Content-Type-Options nosniff" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLCompression off" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLUseStapling on" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLStaplingCache \"shmcb:logs/stapling-cache(150000)\"" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLSessionTickets Off" >> /etc/apache2/conf-available/ssl-params.conf + + cp /etc/apache2/sites-available/default-ssl.conf /etc/apache2/sites-available/default-ssl.conf.bak + sed -i "s/var\/www\/html/var\/www\/$DOMAIN/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "s/etc\/ssl\/certs\/ssl-cert-snakeoil.pem/etc\/ssl\/certs\/apache-selfsigned.crt/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "s/etc\/ssl\/private\/ssl-cert-snakeoil.key/etc\/ssl\/private\/apache-selfsigned.key/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "4i\\\t\tServerName $ip" /etc/apache2/sites-available/default-ssl.conf + sed -i "22i\\\tRedirect permanent \"/\" \"https://$ip/\"" /etc/apache2/sites-available/000-default.conf + a2enmod ssl + a2enmod headers + a2ensite default-ssl + a2enconf ssl-params + systemctl reload apache2 +} +``` + +Next, we are going to create the `db_setup()` function. Inside of it, we are going to create the database, create the user and grant all privileges to the user. + +```bash +db_config () { + mysql -e "CREATE DATABASE $DBNAME;" + mysql -e "GRANT ALL ON $DBNAME.* TO '$DBUSERNAME'@'localhost' IDENTIFIED BY '$DBPASSWORD' WITH GRANT OPTION;" + mysql -e "FLUSH PRIVILEGES;" +} +``` + +Next, we are going to create the `wordpress_config()` function. Inside of it, we are going to download the latest version of WordPress, extract it to the `/var/www/$DOMAIN` directory, create the `wp-config.php` file and append the required content to it. + +```bash +wordpress_config () { + db_config + + + apt install php-curl php-gd php-mbstring php-xml php-xmlrpc php-soap php-intl php-zip -y + systemctl restart apache2 + sed -i "8i\\\t" /etc/apache2/sites-available/$DOMAIN.conf + sed -i "9i\\\t\tAllowOverride All" /etc/apache2/sites-available/$DOMAIN.conf + sed -i "10i\\\t" /etc/apache2/sites-available/$DOMAIN.conf + + a2enmod rewrite + systemctl restart apache2 + + apt install curl + cd /tmp + curl -O https://wordpress.org/latest.tar.gz + tar xzvf latest.tar.gz + touch /tmp/wordpress/.htaccess + cp /tmp/wordpress/wp-config-sample.php /tmp/wordpress/wp-config.php + mkdir /tmp/wordpress/wp-content/upgrade + cp -a /tmp/wordpress/. /var/www/$DOMAIN + chown -R www-data:www-data /var/www/$DOMAIN + find /var/www/$DOMAIN/ -type d -exec chmod 750 {} \; + find /var/www/$DOMAIN/ -type f -exec chmod 640 {} \; + curl -s https://api.wordpress.org/secret-key/1.1/salt/ >> /var/www/$DOMAIN/wp-config.php + echo "define('FS_METHOD', 'direct');" >> /var/www/$DOMAIN/wp-config.php + sed -i "51,58d" /var/www/$DOMAIN/wp-config.php + sed -i "s/database_name_here/$DBNAME/1" /var/www/$DOMAIN/wp-config.php + sed -i "s/username_here/$DBUSERNAME/1" /var/www/$DOMAIN/wp-config.php + sed -i "s/password_here/$DBPASSWORD/1" /var/www/$DOMAIN/wp-config.php +} +``` + +And finally, we are going to create the `execute()` function. Inside of it, we are going to call all the functions we created above. + +```bash +execute () { + lamp_install + apache_virtual_host_setup + ssl_config + wordpress_config +} +``` + +With this, you have the script ready and you are ready to run it. And if you need the full script, you can find it in the next section. + +# The full script + +```bash +#!/bin/bash + +echo 'Please enter your domain of preference without www:' +read DOMAIN +echo "Please enter your Database username:" +read DBUSERNAME +echo "Please enter your Database password:" +read DBPASSWORD +echo "Please enter your Database name:" +read DBNAME + +ip=`hostname -I | cut -f1 -d' '` + +lamp_install () { + apt update -y + apt install ufw + ufw enable + ufw allow OpenSSH + ufw allow in "WWW Full" + + apt install apache2 -y + apt install mariadb-server + mysql_secure_installation -y + apt install php libapache2-mod-php php-mysql -y + sed -i "2d" /etc/apache2/mods-enabled/dir.conf + sed -i "2i\\\tDirectoryIndex index.php index.html index.cgi index.pl index.xhtml index.htm" /etc/apache2/mods-enabled/dir.conf + systemctl reload apache2 + +} + +apache_virtual_host_setup () { + mkdir /var/www/$DOMAIN + chown -R $USER:$USER /var/www/$DOMAIN + + echo "" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerName $DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerAlias www.$DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tServerAdmin webmaster@localhost" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e "\tDocumentRoot /var/www/$DOMAIN" >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e '\tErrorLog ${APACHE_LOG_DIR}/error.log' >> /etc/apache2/sites-available/$DOMAIN.conf + echo -e '\tCustomLog ${APACHE_LOG_DIR}/access.log combined' >> /etc/apache2/sites-available/$DOMAIN.conf + echo "" >> /etc/apache2/sites-available/$DOMAIN.conf + a2ensite $DOMAIN + a2dissite 000-default + systemctl reload apache2 + +} + + +ssl_config () { + openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/private/apache-selfsigned.key -out /etc/ssl/certs/apache-selfsigned.crt + + echo "SSLCipherSuite EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLProtocol All -SSLv2 -SSLv3 -TLSv1 -TLSv1.1" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLHonorCipherOrder On" >> /etc/apache2/conf-available/ssl-params.conf + echo "Header always set X-Frame-Options DENY" >> /etc/apache2/conf-available/ssl-params.conf + echo "Header always set X-Content-Type-Options nosniff" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLCompression off" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLUseStapling on" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLStaplingCache \"shmcb:logs/stapling-cache(150000)\"" >> /etc/apache2/conf-available/ssl-params.conf + echo "SSLSessionTickets Off" >> /etc/apache2/conf-available/ssl-params.conf + + cp /etc/apache2/sites-available/default-ssl.conf /etc/apache2/sites-available/default-ssl.conf.bak + sed -i "s/var\/www\/html/var\/www\/$DOMAIN/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "s/etc\/ssl\/certs\/ssl-cert-snakeoil.pem/etc\/ssl\/certs\/apache-selfsigned.crt/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "s/etc\/ssl\/private\/ssl-cert-snakeoil.key/etc\/ssl\/private\/apache-selfsigned.key/1" /etc/apache2/sites-available/default-ssl.conf + sed -i "4i\\\t\tServerName $ip" /etc/apache2/sites-available/default-ssl.conf + sed -i "22i\\\tRedirect permanent \"/\" \"https://$ip/\"" /etc/apache2/sites-available/000-default.conf + a2enmod ssl + a2enmod headers + a2ensite default-ssl + a2enconf ssl-params + systemctl reload apache2 +} + +db_config () { + mysql -e "CREATE DATABASE $DBNAME;" + mysql -e "GRANT ALL ON $DBNAME.* TO '$DBUSERNAME'@'localhost' IDENTIFIED BY '$DBPASSWORD' WITH GRANT OPTION;" + mysql -e "FLUSH PRIVILEGES;" +} + +wordpress_config () { + db_config + + + apt install php-curl php-gd php-mbstring php-xml php-xmlrpc php-soap php-intl php-zip -y + systemctl restart apache2 + sed -i "8i\\\t" /etc/apache2/sites-available/$DOMAIN.conf + sed -i "9i\\\t\tAllowOverride All" /etc/apache2/sites-available/$DOMAIN.conf + sed -i "10i\\\t" /etc/apache2/sites-available/$DOMAIN.conf + + a2enmod rewrite + systemctl restart apache2 + + apt install curl + cd /tmp + curl -O https://wordpress.org/latest.tar.gz + tar xzvf latest.tar.gz + touch /tmp/wordpress/.htaccess + cp /tmp/wordpress/wp-config-sample.php /tmp/wordpress/wp-config.php + mkdir /tmp/wordpress/wp-content/upgrade + cp -a /tmp/wordpress/. /var/www/$DOMAIN + chown -R www-data:www-data /var/www/$DOMAIN + find /var/www/$DOMAIN/ -type d -exec chmod 750 {} \; + find /var/www/$DOMAIN/ -type f -exec chmod 640 {} \; + curl -s https://api.wordpress.org/secret-key/1.1/salt/ >> /var/www/$DOMAIN/wp-config.php + echo "define('FS_METHOD', 'direct');" >> /var/www/$DOMAIN/wp-config.php + sed -i "51,58d" /var/www/$DOMAIN/wp-config.php + sed -i "s/database_name_here/$DBNAME/1" /var/www/$DOMAIN/wp-config.php + sed -i "s/username_here/$DBUSERNAME/1" /var/www/$DOMAIN/wp-config.php + sed -i "s/password_here/$DBPASSWORD/1" /var/www/$DOMAIN/wp-config.php +} + +execute () { + lamp_install + apache_virtual_host_setup + ssl_config + wordpress_config +} +``` + +## Summary + +The script does the following: + + * Install LAMP + * Create a virtual host + * Configure SSL + * Install WordPress + * Configure WordPress + +With this being said, I hope you enjoyed this example. If you have any questions, please feel free to ask me directly at [@denctl](https://twitter.com/denctl). diff --git a/docs/.Bash-Scripting/100-bash-wrap-up.md b/docs/.Bash-Scripting/100-bash-wrap-up.md new file mode 100755 index 0000000..bf808d8 --- /dev/null +++ b/docs/.Bash-Scripting/100-bash-wrap-up.md @@ -0,0 +1,15 @@ +# Wrap Up + +Congratulations! You have just completed the Bash basics guide! + +If you found this useful, be sure to star the project on [GitHub](https://github.com/bobbyiliev/introduction-to-bash-scripting)! + +If you have any suggestions for improvements, make sure to contribute pull requests or open issues. + +In this introduction to Bash scripting book, we just covered the basics, but you still have enough under your belt to start wringing some awesome scripts and automating daily tasks! + +As a next step try writing your own script and share it with the world! This is the best way to learn any new programming or scripting language! + +In case that this book inspired you to write some cool Bash scripts, make sure to tweet about it and tag [@bobbyiliev_](https://twitter.com) so that we could check it out! + +Congrats again on completing this book! diff --git a/docs/.recycle/extras.md b/docs/.recycle/extras.md new file mode 100755 index 0000000..459555f --- /dev/null +++ b/docs/.recycle/extras.md @@ -0,0 +1,82 @@ +# A Linux Learning Playground Situation + +!["Shinobi Academy Linux"](/cover.png) + +wanna play with the application in this picture? connect to the server using the instructions below and run the command `hollywood` + +## Introduction: + +Welcome, aspiring Linux ninjas! This tutorial will guide you through accessing Shinobi Academy Linux, a custom-built server designed to provide a safe and engaging environment for you to learn and experiment with Linux. Brought to you by Softwareshinobi ([https://softwareshinobi.digital/](https://softwareshinobi.digital/)), this server is your gateway to the exciting world of open-source exploration. + +## What You'll Learn: + +* Connecting to a Linux server (using SSH) +* Basic Linux commands (navigation, listing files, etc.) +* Exploring pre-installed tools like cmatrix and hollywood + +## What You'll Need: + +* A computer with internet access +* An SSH client (built-in on most Linux and macOS systems, downloadable for Windows) + +## About Shinobi Academy: + +Shinobi Academy, the online learning platform brought to you by Softwareshinobi! + +Designed to empower aspiring tech enthusiasts, Shinobi Academy offers a comprehensive range of courses and resources to equip you with the skills you need to excel in the ever-evolving world of technology. + +## Connecting to Shinobi Academy Linux: + +1. Open your SSH client. +2. Enter the following command (including the port number): + +``` +ssh -p 2222 shinobi@linux.softwareshinobi.digital +``` + +3. When prompted, enter the password "shinobi". + +``` +username / shinobi +``` + +``` +password / shinobi +``` + +**Congratulations!** You're now connected to Shinobi Academy Linux. + +## Exploring the Server: + +Once connected, you can use basic Linux commands to navigate the system and explore its features. Here are a few examples: + +* **`ls`:** Lists files and directories in the current directory. +* **`cd`:** Changes directory. For example, `cd Desktop` will move you to the Desktop directory (if it exists). +* **`pwd`:** Shows the current working directory. +* **`man` followed by a command name:** Provides detailed information on a specific command (e.g., `man ls`). + +## Pre-installed Goodies: + +Shinobi Academy Linux comes pre-installed with some interesting tools to enhance your learning experience: + +* **`cmatrix`:** Simulates the iconic falling code effect from the movie "The Matrix". +* **`hollywood`:** Creates a variety of dynamic text effects on your terminal. + +**Experimenting with these tools is a great way to explore the possibilities of Linux.** + +## Conclusion: + +By following these steps, you've successfully connected to Shinobi Academy Linux and begun your journey into the world of Linux. Use this platform to explore, experiment, and build your Linux skills! + +A big thanks to Gemini for putting together these awesome docs! + +## Master Linux Like a Pro: 1-on-1 Tutoring: + +**Tired of fumbling in the terminal?** Imagine wielding Linux commands with ease, managing servers like a corporate ninja – just like my government and corporate gigs. + +**1-on-1 tutoring unlocks your potential:** + +* **Terminal mastery:** Conquer the command line and automate tasks like a pro. +* **Become a command jedi:** Craft commands with lightning speed, streamlining your workflow. + +**Ready to transform your skills?** [Learn More!](tutor.softwareshinobi.digital/linux) diff --git a/docs/.recycle/introduction-to-bash-scripting-main.zip b/docs/.recycle/introduction-to-bash-scripting-main.zip new file mode 100755 index 0000000..0bd74ac Binary files /dev/null and b/docs/.recycle/introduction-to-bash-scripting-main.zip differ diff --git a/docs/.recycle/videos/commands/the-deluser-command.mp4 b/docs/.recycle/videos/commands/the-deluser-command.mp4 new file mode 100755 index 0000000..56c96d1 Binary files /dev/null and b/docs/.recycle/videos/commands/the-deluser-command.mp4 differ diff --git a/docs/.recycle/videos/commands/the-zip-command.jpg b/docs/.recycle/videos/commands/the-zip-command.jpg new file mode 100755 index 0000000..3f3743f Binary files /dev/null and b/docs/.recycle/videos/commands/the-zip-command.jpg differ diff --git a/docs/.recycle/videos/commands/the-zip-command.mp4 b/docs/.recycle/videos/commands/the-zip-command.mp4 new file mode 100755 index 0000000..de13094 Binary files /dev/null and b/docs/.recycle/videos/commands/the-zip-command.mp4 differ diff --git a/docs/Linux-Commands/.recycle/008-the-cal-command.md b/docs/Linux-Commands/.recycle/008-the-cal-command.md new file mode 100755 index 0000000..75d62ce --- /dev/null +++ b/docs/Linux-Commands/.recycle/008-the-cal-command.md @@ -0,0 +1,59 @@ +# The `cal` Command +The `cal` command displays a formatted calendar in the terminal. If no options are specified, cal displays the current month, with the current day highlighted. + +### Syntax: +``` +cal [general options] [-jy] [[month] year] +``` + +### Options: +|**Option**|**Description**| +|:--|:--| +|`-h`|Don't highlight today's date.| +|`-m month`|Specify a month to display. The month specifier is a full month name (e.g., February), a month abbreviation of at least three letters (e.g., Feb), or a number (e.g., 2). If you specify a number, followed by the letter "f" or "p", the month of the following or previous year, respectively, display. For instance, `-m 2f` displays February of next year.| +|`-y year`|Specify a year to display. For example, `-y 1970` displays the entire calendar of the year 1970.| +|`-3`|Display last month, this month, and next month.| +|`-1`|Display only this month. This is the default.| +|`-A num`|Display num months occurring after any months already specified. For example, `-3 -A 3` displays last month, this month, and four months after this one; and `-y 1970 -A 2` displays every month in 1970, and the first two months of 1971.| +|`-B num`|Display num months occurring before any months already specified. For example, `-3 -B 2` displays the previous three months, this month, and next month.| +|`-d YYYY-MM`|Operate as if the current month is number MM of year YYYY.| + +### Examples: +1. Display the calendar for this month, with today highlighted. +``` +cal +``` + +2. Same as the previous command, but do not highlight today. +``` +cal -h +``` + +3. Display last month, this month, and next month. +``` +cal -3 +``` +4. Display this entire year's calendar. +``` +cal -y +``` + +5. Display the entire year 2000 calendar. +``` +cal -y 2000 +``` + +6. Same as the previous command. +``` +cal 2000 +``` + +7. Display the calendar for December of this year. +``` +cal -m [December, Dec, or 12] +``` + +10. Display the calendar for December 2000. +``` +cal 12 2000 +``` diff --git a/docs/Linux-Commands/.recycle/009-the-bc-command.md b/docs/Linux-Commands/.recycle/009-the-bc-command.md new file mode 100755 index 0000000..4db506b --- /dev/null +++ b/docs/Linux-Commands/.recycle/009-the-bc-command.md @@ -0,0 +1,94 @@ +# The `bc` command + +The `bc` command provides the functionality of being able to perform mathematical calculations through the command line. + +### Examples: + +1 . Arithmetic: + +``` +Input : $ echo "11+5" | bc +Output : 16 +``` +2 . Increment: +- var –++ : Post increment operator, the result of the variable is used first and then the variable is incremented. +- – ++var : Pre increment operator, the variable is increased first and then the result of the variable is stored. + +``` +Input: $ echo "var=3;++var" | bc +Output: 4 +``` +3 . Decrement: +- var – – : Post decrement operator, the result of the variable is used first and then the variable is decremented. +- – – var : Pre decrement operator, the variable is decreased first and then the result of the variable is stored. + +``` +Input: $ echo "var=3;--var" | bc +Output: 2 +``` +4 . Assignment: +- var = value : Assign the value to the variable +- var += value : similar to var = var + value +- var -= value : similar to var = var – value +- var *= value : similar to var = var * value +- var /= value : similar to var = var / value +- var ^= value : similar to var = var ^ value +- var %= value : similar to var = var % value + +``` +Input: $ echo "var=4;var" | bc +Output: 4 +``` +5 . Comparison or Relational: +- If the comparison is true, then the result is 1. Otherwise,(false), returns 0 +- expr1expr2 : Result is 1, if expr1 is strictly greater than expr2. +- expr1>=expr2 : Result is 1, if expr1 is greater than or equal to expr2. +- expr1==expr2 : Result is 1, if expr1 is equal to expr2. +- expr1!=expr2 : Result is 1, if expr1 is not equal to expr2. + +``` +Input: $ echo "6<4" | bc +Output: 0 +``` +``` +Input: $ echo "2==2" | bc +Output: 1 +``` +6 . Logical or Boolean: + +- expr1 && expr2 : Result is 1, if both expressions are non-zero. +- expr1 || expr2 : Result is 1, if either expression is non-zero. +- ! expr : Result is 1, if expr is 0. + +``` +Input: $ echo "! 1" | bc +Output: 0 + +Input: $ echo "10 && 5" | bc +Output: 1 +``` + +### Syntax: + +``` +bc [ -hlwsqv ] [long-options] [ file ... ] +``` + +### Additional Flags and their Functionalities: + +*Note: This does not include an exhaustive list of options.* + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-i`|`--interactive`|Force interactive mode| +|`-l`|`--mathlib`|Use the predefined math routines| +|`-q`|`--quiet`|Opens the interactive mode for bc without printing the header| +|`-s`|`--standard`|Treat non-standard bc constructs as errors| +|`-w`|`--warn`|Provides a warning if non-standard bc constructs are used| + +### Notes: + +1. The capabilities of `bc` can be further appreciated if used within a script. Aside from basic arithmetic operations, `bc` supports increments/decrements, complex calculations, logical comparisons, etc. +2. Two of the flags in `bc` refer to non-standard constructs. If you evaluate `100>50 | bc` for example, you will get a strange warning. According to the POSIX page for bc, relational operators are only valid if used within an `if`, `while`, or `for` statement. diff --git a/docs/Linux-Commands/.recycle/011-the-help-command.md b/docs/Linux-Commands/.recycle/011-the-help-command.md new file mode 100755 index 0000000..898cbe4 --- /dev/null +++ b/docs/Linux-Commands/.recycle/011-the-help-command.md @@ -0,0 +1,31 @@ +# The `help` command +The `help` command displays information about builtin commands. +Display information about builtin commands. + +If a `PATTERN` is specified, this command gives detailed help on all commands matching the `PATTERN`, otherwise the list of available help topics is printed. + +## Syntax +```bash +$ help [-dms] [PATTERN ...] +``` + +## Options +|**Option**|**Description**| +|:--|:--| +|`-d`|Output short description for each topic.| +|`-m`|Display usage in pseudo-manpage format.| +|`-s`|Output only a short usage synopsis for each topic matching the provided `PATTERN`.| + +## Examples of uses: +1. We get the complete information about the `cd` command +```bash +$ help cd +``` +2. We get a short description about the `pwd` command +```bash +$ help -d pwd +``` +3. We get the syntax of the `cd` command +```bash +$ help -s cd +``` diff --git a/docs/Linux-Commands/.recycle/012-the-factor-command.md b/docs/Linux-Commands/.recycle/012-the-factor-command.md new file mode 100755 index 0000000..4c6817d --- /dev/null +++ b/docs/Linux-Commands/.recycle/012-the-factor-command.md @@ -0,0 +1,29 @@ +# The `factor` command +The `factor` command prints the prime factors of each specified integer `NUMBER`. If none are specified on the command line, it will read them from the standard input. + +## Syntax +```bash +$ factor [NUMBER]... +``` +OR: +```bash +$ factor OPTION +``` + +## Options +|**Option**|**Description**| +|:--|:--| +|`--help`|Display this a help message and exit.| +|`--version`|Output version information and exit.| + +## Examples + +1. Print prime factors of a prime number. +```bash +$ factor 50 +``` + +2. Print prime factors of a non-prime number. +```bash +$ factor 75 +``` diff --git a/docs/Linux-Commands/.recycle/016-the-whatis-command.md b/docs/Linux-Commands/.recycle/016-the-whatis-command.md new file mode 100755 index 0000000..aaf9454 --- /dev/null +++ b/docs/Linux-Commands/.recycle/016-the-whatis-command.md @@ -0,0 +1,32 @@ +# The `whatis` command + +The `whatis` command is used to display one-line manual page descriptions for commands. +It can be used to get a basic understanding of what a (unknown) command is used for. + +### Examples of uses: + +1. To display what `ls` is used for: + +``` +whatis ls +``` + +2. To display the use of all commands which start with `make`, execute the following: + +``` +whatis -w make* +``` + +### Syntax: + +``` +whatis [-OPTION] [KEYWORD] +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-d`|`--debug`|Show debugging messages| +|`-r`|`--regex`|Interpret each keyword as a regex| +|`-w`|`--wildcard`|The keyword(s) contain wildcards| \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/017-the-who-command.md b/docs/Linux-Commands/.recycle/017-the-who-command.md new file mode 100755 index 0000000..59d12ad --- /dev/null +++ b/docs/Linux-Commands/.recycle/017-the-who-command.md @@ -0,0 +1,33 @@ +# The `who` command + +The `who` command lets you print out a list of logged-in users, the current run level of the system and the time of last system boot. + +### Examples + +1. Print out all details of currently logged-in users + +``` +who -a +``` + +2. Print out the list of all dead processes + +``` +who -d -H +``` + +### Syntax: + +``` +who [options] [filename] +``` + +### Additional Flags and their Functionalities + +|**Short Flag** |**Description** | +|---|---| +| `-r` |prints all the current runlevel | +| `-d` |print all the dead processes | +|`-q`|print all the login names and total number of logged on users | +|`-h`|print the heading of the columns displayed | +|`-b`|print the time of last system boot | \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/018-the-free-command.md b/docs/Linux-Commands/.recycle/018-the-free-command.md new file mode 100755 index 0000000..7e77937 --- /dev/null +++ b/docs/Linux-Commands/.recycle/018-the-free-command.md @@ -0,0 +1,33 @@ +018-the-free-command.md + +# The `free` command + +The `free` command in Linux/Unix is used to show memory (RAM/SWAP) information. + +# Usage + +## Show memory usage + +**Action:** +--- Output the memory usage - available and used, as well as swap + +**Details:** +--- Outputted values are not human-readable (are in bytes) + +**Command:** +``` +free +``` + +## Show memory usage in human-readable form + +**Action:** +--- Output the memory usage - available and used, as well as swap + +**Details:** +--- Outputted values ARE human-readable (are in GB / MB) + +**Command:** +``` +free -h +``` \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/020-the-sl-command.md b/docs/Linux-Commands/.recycle/020-the-sl-command.md new file mode 100755 index 0000000..0198708 --- /dev/null +++ b/docs/Linux-Commands/.recycle/020-the-sl-command.md @@ -0,0 +1,19 @@ +# The `sl` command + +The `sl` command in Linux is a humorous program that runs a steam locomotive(sl) across your terminal. + +![image](https://i.imgur.com/CInBHak.png) + +## Installation + +Install the package before running. + +``` +sudo apt install sl +``` + +## Syntax + +``` +sl +``` diff --git a/docs/Linux-Commands/.recycle/022-the-finger-command.md b/docs/Linux-Commands/.recycle/022-the-finger-command.md new file mode 100755 index 0000000..bef125d --- /dev/null +++ b/docs/Linux-Commands/.recycle/022-the-finger-command.md @@ -0,0 +1,76 @@ + +# The `finger` command + +The `finger` displays information about the system users. + +### Examples: + +1. View detail about a particular user. + +``` +finger abc +``` +*Output* +``` +Login: abc Name: (null) +Directory: /home/abc Shell: /bin/bash +On since Mon Nov 1 18:45 (IST) on :0 (messages off) +On since Mon Nov 1 18:46 (IST) on pts/0 from :0.0 +New mail received Fri May 7 10:33 2013 (IST) +Unread since Sat Jun 7 12:59 2003 (IST) +No Plan. +``` + +2. View login details and Idle status about an user + +``` +finger -s root +``` +*Output* +``` +Login Name Tty Idle Login Time Office Office Phone +root root *1 19d Wed 17:45 +root root *2 3d Fri 16:53 +root root *3 Mon 20:20 +root root *ta 2 Tue 15:43 +root root *tb 2 Tue 15:44 +``` +### Syntax: + +``` +finger [-l] [-m] [-p] [-s] [username] +``` + + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-l`|Force long output format.| +|`-m`|Match arguments only on user name (not first or last name).| +|`-p`|Suppress printing of the .plan file in a long format printout.| +|`-s`|Force short output format.| + +### Additional Information +**Default Format** + +The default format includes the following items: + +Login name +Full username +Terminal name +Write status (an * (asterisk) before the terminal name indicates that write permission is denied) +For each user on the host, the default information list also includes, if known, the following items: + +Idle time (Idle time is minutes if it is a single integer, hours and minutes if a : (colon) is present, or days and hours if a “d” is present.) +Login time +Site-specific information + +**Longer Format** + +A longer format is used by the finger command whenever a list of user’s names is given. (Account names as well as first and last names of users are accepted.) This format is multiline, and includes all the information described above along with the following: + +User’s $HOME directory +User’s login shell +Contents of the .plan file in the user’s $HOME directory +Contents of the .project file in the user’s $HOME directory diff --git a/docs/Linux-Commands/.recycle/026-the-w-command.md b/docs/Linux-Commands/.recycle/026-the-w-command.md new file mode 100755 index 0000000..86a3148 --- /dev/null +++ b/docs/Linux-Commands/.recycle/026-the-w-command.md @@ -0,0 +1,56 @@ +# The `w` command + +The `w` command displays information about the users that are currently active on the machine and their [processes](https://www.computerhope.com/jargon/p/process.htm). + +### Examples: + +1. Running the `w` command without [arguments](https://www.computerhope.com/jargon/a/argument.htm) shows a list of logged on users and their processes. + +``` +w +``` + + +2. Show information for the user named *hope*. + +``` +w hope +``` + +### Syntax: + +``` +finger [-l] [-m] [-p] [-s] [username] +``` + + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-h`|`--no-header`|Don't print the header.| +|`-u`|`--no-current`|Ignores the username while figuring out the current process and cpu times. *(To see an example of this, switch to the root user with `su` and then run both `w` and `w -u`.)*| +|`-s`|`--short`|Display abbreviated output *(don't print the login time, JCPU or PCPU times).*| +|`-f`|`--from`|Toggle printing the from *(remote hostname)* field. The default as released is for the from field to not be printed, although your system administrator or distribution maintainer may have compiled a version where the from field is shown by default.| +|`--help`|
-
|Display a help message, and exit.| +|`-V`|`--version`|Display version information, and exit.| +|`-o`|`--old-style`|Old style output *(prints blank space for idle times less than one minute)*.| +|*`user`*|
-
|Show information about the specified the user only.| + + +### Additional Information + +The [header](https://www.computerhope.com/jargon/h/header.htm) of the output shows (in this order): the current time, how long the system has been running, how many users are currently logged on, and the system [load](https://www.computerhope.com/jargon/l/load.htm) averages for the past 1, 5, and 15 minutes. + +The following entries are displayed for each user: +- login name the [tty](https://www.computerhope.com/jargon/t/tty.htm) +- name the [remote](https://www.computerhope.com/jargon/r/remote.htm) +- [host](https://www.computerhope.com/jargon/h/hostcomp.htm) they are +- logged in from the amount of time they are logged in their +- [idle](https://www.computerhope.com/jargon/i/idle.htm) time JCPU +- PCPU +- [command line](https://www.computerhope.com/jargon/c/commandi.htm) of their current process + +The JCPU time is the time used by all processes attached to the tty. It does not include past background jobs, but does include currently running background jobs. + +The PCPU time is the time used by the current process, named in the "what" field. diff --git a/docs/Linux-Commands/.recycle/029-the-login-command.md b/docs/Linux-Commands/.recycle/029-the-login-command.md new file mode 100755 index 0000000..5ed8683 --- /dev/null +++ b/docs/Linux-Commands/.recycle/029-the-login-command.md @@ -0,0 +1,28 @@ +# The `login` Command + +The `login` command initiates a user session. + +## Syntax + +```bash +$ login [-p] [-h host] [-H] [-f username|username] +``` + +## Flags and their functionalities + +|**Short Flag** |**Description** | +|---|---| +| `-f` |Used to skip a login authentication. This option is usually used by the getty(8) autologin feature. | +| `-h` | Used by other servers (such as telnetd(8) to pass the name of the remote host to login so that it can be placed in utmp and wtmp. Only the superuser is allowed use this option. | +|`-p`|Used by getty(8) to tell login to preserve the environment. | +|`-H`|Used by other servers (for example, telnetd(8)) to tell login that printing the hostname should be suppressed in the login: prompt. | +|`--help`|Display help text and exit.| +|`-v`|Display version information and exit.| + +## Examples + +To log in to the system as user abhishek, enter the following at the login prompt: +```bash +$ login: abhishek +``` +If a password is defined, the password prompt appears. Enter your password at this prompt. diff --git a/docs/Linux-Commands/.recycle/030-the-lscpu-command.md b/docs/Linux-Commands/.recycle/030-the-lscpu-command.md new file mode 100755 index 0000000..763c992 --- /dev/null +++ b/docs/Linux-Commands/.recycle/030-the-lscpu-command.md @@ -0,0 +1,52 @@ +# `lscpu` command + +`lscpu` in Linux/Unix is used to display CPU Architecture info. `lscpu` gathers CPU architecture information from `sysfs` and `/proc/cpuinfo` files. + +For example : + ``` + manish@godsmack:~$ lscpu + Architecture: x86_64 + CPU op-mode(s): 32-bit, 64-bit + Byte Order: Little Endian + CPU(s): 4 + On-line CPU(s) list: 0-3 + Thread(s) per core: 2 + Core(s) per socket: 2 + Socket(s): 1 + NUMA node(s): 1 + Vendor ID: GenuineIntel + CPU family: 6 + Model: 142 + Model name: Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz + Stepping: 9 + CPU MHz: 700.024 + CPU max MHz: 3100.0000 + CPU min MHz: 400.0000 + BogoMIPS: 5399.81 + Virtualization: VT-x + L1d cache: 32K + L1i cache: 32K + L2 cache: 256K + L3 cache: 3072K + NUMA node0 CPU(s): 0-3 + ``` + + +## Options + +`-a, --all` + Include lines for online and offline CPUs in the output (default for -e). This option may only specified together with option -e or -p. + For example: `lsof -a` + +`-b, --online` + Limit the output to online CPUs (default for -p). This option may only be specified together with option -e or -p. + For example: `lscpu -b` + +`-c, --offline` + Limit the output to offline CPUs. This option may only be specified together with option -e or -p. + +`-e, --extended [=list]` + Display the CPU information in human readable format. + For example: `lsof -e` + +For more info: use `man lscpu` or `lscpu --help` diff --git a/docs/Linux-Commands/.recycle/037-the-printenv-command.md b/docs/Linux-Commands/.recycle/037-the-printenv-command.md new file mode 100755 index 0000000..c8cfcb6 --- /dev/null +++ b/docs/Linux-Commands/.recycle/037-the-printenv-command.md @@ -0,0 +1,37 @@ +# The `printenv` command + +The `printenv` prints the values of the specified [environment _VARIABLE(s)_](https://www.computerhope.com/jargon/e/envivari.htm). If no [_VARIABLE_](https://www.computerhope.com/jargon/v/variable.htm) is specified, print name and value pairs for them all. + +### Examples: + +1. Display the values of all environment variables. + +``` +printenv +``` + +2. Display the location of the current user's [home directory](https://www.computerhope.com/jargon/h/homedir.htm). +``` +printenv HOME +``` + +3. To use the `--null` command line option as the terminating character between output entries. +``` +printenv --null SHELL HOME +``` +*NOTE: By default, the* `printenv` *command uses newline as the terminating character between output entries.* + + +### Syntax: + +``` +printenv [OPTION]... PATTERN... +``` + + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-0`|`--null`|End each output line with **0** byte rather than [newline](https://www.computerhope.com/jargon/n/newline.htm).| +|`--help`|
-
|Display a help message, and exit.| diff --git a/docs/Linux-Commands/.recycle/042-the-ip-command.md b/docs/Linux-Commands/.recycle/042-the-ip-command.md new file mode 100755 index 0000000..4f1a323 --- /dev/null +++ b/docs/Linux-Commands/.recycle/042-the-ip-command.md @@ -0,0 +1,39 @@ +# The `ip` command + +The `ip` command is present in the net-tools which is used for performing several network administration tasks. IP stands for Internet Protocol. This command is used to show or manipulate routing, devices, and tunnels. It can perform tasks like configuring and modifying the default and static routing, setting up tunnel over IP, listing IP addresses and property information, modifying the status of the interface, assigning, deleting and setting up IP addresses and routes. + +### Examples: + +1. To assign an IP Address to a specific interface (eth1) : + +``` + ip addr add 192.168.50.5 dev eth1 +``` + +2. To show detailed information about network interfaces like IP Address, MAC Address information etc. : + +``` +ip addr show +``` + +### Syntax: + +``` +ip [ OPTIONS ] OBJECT { COMMAND | help } +``` + + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-a`| Display and modify IP Addresses | +|`-l`|Display and modify network interfaces | +|`-r`|Display and alter the routing table| +|`-n`|Display and manipulate neighbor objects (ARP table) | +|`-ru`|Rule in routing policy database.| +|`-s`|Output more information. If the option appears twice or more, the amount of information increases | +|`-f`|Specifies the protocol family to use| +|`-r`|Use the system's name resolver to print DNS names instead of host addresses| +|`-c`|To configure color output | + diff --git a/docs/Linux-Commands/.recycle/048-the-last-command.md b/docs/Linux-Commands/.recycle/048-the-last-command.md new file mode 100755 index 0000000..d3fb9a2 --- /dev/null +++ b/docs/Linux-Commands/.recycle/048-the-last-command.md @@ -0,0 +1,23 @@ +# The `last` command + +This command shows you a list of all the users that have logged in and out since the creation of the `var/log/wtmp` file. There are also some parameters you can add which will show you for example when a certain user has logged in and how long he was logged in for. + +If you want to see the last 5 logs, just add `-5` to the command like this: + +``` +last -5 +``` + +And if you want to see the last 10, add `-10`. + +Another cool thing you can do is if you add `-F` you can see the login and logout time including the dates. + +``` +last -F +``` + +There are quite a lot of stuff you can view with this command. If you need to find out more about this command you can run: + +``` +last --help +``` diff --git a/docs/Linux-Commands/.recycle/049-the-locate-command.md b/docs/Linux-Commands/.recycle/049-the-locate-command.md new file mode 100755 index 0000000..619809a --- /dev/null +++ b/docs/Linux-Commands/.recycle/049-the-locate-command.md @@ -0,0 +1,93 @@ +# The `locate` command + +The `locate` command searches the file system for files and directories whose name matches a given pattern through a database file that is generated by the `updatedb` command. + +### Examples: + +1. Running the `locate` command to search for a file named `.bashrc`. + +``` +locate .bashrc +``` +*Output* +``` +/etc/bash.bashrc +/etc/skel/.bashrc +/home/linuxize/.bashrc +/usr/share/base-files/dot.bashrc +/usr/share/doc/adduser/examples/adduser.local.conf.examples/bash.bashrc +/usr/share/doc/adduser/examples/adduser.local.conf.examples/skel/dot.bashrc +``` +The `/root/.bashrc` file will not be shown because we ran the command as a normal user that doesn’t have access permissions to the `/root` directory. + +If the result list is long, for better readability, you can pipe the output to the [`less`](https://linuxize.com/post/less-command-in-linux/) command: + +``` +locate .bashrc | less +``` + +2. To search for all `.md` files on the system +``` +locate *.md +``` +3. To search all `.py` files and display only 10 results +``` +locate -n 10 *.py +``` +4. To performs case-insensitive search. +``` +locate -i readme.md +``` +*Output* +``` +/home/linuxize/p1/readme.md +/home/linuxize/p2/README.md +/home/linuxize/p3/ReadMe.md +``` +5. To return the number of all files containing `.bashrc` in their name. +``` +locate -c .bashrc +``` +*Output* +``` +6 +``` +6. The following would return only the existing `.json` files on the file system. +``` +locate -e *.json +``` +7. To run a more complex search the `-r` (`--regexp`) option is used. +To search for all `.mp4` and `.avi` files on your system and ignore case. +``` +locate --regex -i "(\.mp4|\.avi)" +``` + +### Syntax: + +``` +1. locate [OPTION]... PATTERN... +``` + + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-A`|`--all`|It is used to display only entries that match all PATTERNs instead of requiring only one of them to match.| +|`-b`|`--basename`|It is used to match only the base name against the specified patterns.| +|`-c`|`--count`|It is used for writing the number matching entries instead of writing file names on standard output.| +|`-d`|`--database DBPATH`|It is used to replace the default database with DBPATH.| +|`-e`|`--existing`|It is used to display only entries that refer to existing files during the command is executed.| +|`-L`|`--follow`|If the `--existing` option is specified, It is used for checking whether files exist and follow trailing symbolic links. It will omit the broken symbolic links to the output. This is the default behavior. The opposite behavior can be specified using the `--nofollow` option.| +|`-h`|`--help`|It is used to display the help documentation that contains a summary of the available options.| +|`-i`|`--ignore-case`|It is used to ignore case sensitivity of the specified patterns.| +|`-p`|`--ignore-spaces`|It is used to ignore punctuation and spaces when matching patterns.| +|`-t`|`--transliterate`|It is used to ignore accents using iconv transliteration when matching patterns.| +|`-l`|`--limit, -n LIMIT`|If this option is specified, the command exit successfully after finding LIMIT entries.| +|`-m`|`--mmap`|It is used to ignore the compatibility with BSD, and GNU locate.| +|`-0`|`--null`|It is used to separate the entries on output using the ASCII NUL character instead of writing each entry on a separate line.| +|`-S`|`--statistics`|It is used to write statistics about each read database to standard output instead of searching for files.| +|`-r`|`--regexp REGEXP`|It is used for searching a basic regexp REGEXP.| +|`--regex`|
-
|It is used to describe all PATTERNs as extended regular expressions.| +|`-V`|`--version`|It is used to display the version and license information.| +|`-w`|` --wholename`|It is used for matching only the whole path name in specified patterns.| diff --git a/docs/Linux-Commands/.recycle/050-the-iostat-command.md b/docs/Linux-Commands/.recycle/050-the-iostat-command.md new file mode 100755 index 0000000..4040dea --- /dev/null +++ b/docs/Linux-Commands/.recycle/050-the-iostat-command.md @@ -0,0 +1,47 @@ +# The `iostat` command + +The `iostat` command in Linux is used for monitoring system input/output statistics for devices and partitions. It monitors system input/output by observing the time the devices are active in relation to their average transfer rates. The iostat produce reports may be used to change the system configuration to raised balance the input/output between the physical disks. iostat is being included in sysstat package. If you don’t have it, you need to install first. + +### Syntax: + +```[linux] +iostat [ -c ] [ -d ] [ -h ] [ -N ] [ -k | -m ] [ -t ] [ -V ] [ -x ] + [ -z ] [ [ [ -T ] -g group_name ] { device [...] | ALL } ] + [ -p [ device [,...] | ALL ] ] [ interval [ count ] ] +``` + +### Examples: + +1. Display a single history-since-boot report for all CPU and Devices: +```[linux] +iostat -d 2 +``` + +2. Display a continuous device report at two-second intervals: +```[linux] +iostat -d 2 6 +``` + +3.Display, for all devices, six reports at two-second intervals: +```[linux] +iostat -x sda sdb 2 6 +``` + +4.Display, for devices sda and sdb, six extended reports at two-second intervals: +```[linux] +iostat -p sda 2 6 +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Description** | +| :------------------------------ | :--------------------------------------------------------- | +| `-x` | Show more details statistics information. | +| `-c` | Show only the cpu statistic. | +| `-d` | Display only the device report | +| `-xd | Show extended I/O statistic for device only. | +| `-k` | Capture the statistics in kilobytes or megabytes. | +| `-k23` | Display cpu and device statistics with delay. | +| `-j ID mmcbkl0 sda6 -x -m 2 2` | Display persistent device name statistics. | +| `-p ` | Display statistics for block devices. | +| `-N ` | Display lvm2 statistic information. | diff --git a/docs/Linux-Commands/.recycle/059-the-sort-command.md b/docs/Linux-Commands/.recycle/059-the-sort-command.md new file mode 100755 index 0000000..ed3466c --- /dev/null +++ b/docs/Linux-Commands/.recycle/059-the-sort-command.md @@ -0,0 +1,77 @@ +# The `sort` command + +the `sort` command is used to sort a file, arranging the records in a particular order. By default, the sort command sorts a file assuming the contents are ASCII. Using options in the sort command can also be used to sort numerically. + +### Examples: + +Suppose you create a data file with name file.txt: +``` +Command : +$ cat > file.txt +abhishek +chitransh +satish +rajan +naveen +divyam +harsh +``` + +Sorting a file: Now use the sort command + +Syntax : + +``` +sort filename.txt +``` + +``` +Command: +$ sort file.txt + +Output : +abhishek +chitransh +divyam +harsh +naveen +rajan +satish +``` + +Note: This command does not actually change the input file, i.e. file.txt. + + +### The sort function on a file with mixed case content + +i.e. uppercase and lower case: When we have a mix file with both uppercase and lowercase letters then first the upper case letters would be sorted following with the lower case letters. + + +Example: + +Create a file mix.txt + + +``` +Command : +$ cat > mix.txt +abc +apple +BALL +Abc +bat +``` +Now use the sort command + +``` +Command : +$ sort mix.txt +Output : +Abc +BALL +abc +apple +bat +``` + + diff --git a/docs/Linux-Commands/.recycle/060-the-paste-command.md b/docs/Linux-Commands/.recycle/060-the-paste-command.md new file mode 100755 index 0000000..a489087 --- /dev/null +++ b/docs/Linux-Commands/.recycle/060-the-paste-command.md @@ -0,0 +1,33 @@ +# The `paste` command + +The `paste` command writes lines of two or more files, sequentially and separated by TABs, to the standard output + +### Syntax: + +```[linux] +paste [OPTIONS]... [FILE]... +``` + +### Examples: + +1. To paste two files + +```[linux] +paste file1 file2 +``` + +2. To paste two files using new line as delimiter + +```[linux] +paste -d '\n' file1 file2 +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :----------------- | :-------------------------- | :-------------------------------------------------------------------------------------------------------------------------------- | +| `-d` | `--delimiter` | use charater of TAB | +| `-s` | `--serial` | paste one file at a time instead of in parallel | +| `-z` | `--zero-terminated` | set line delimiter to NUL, not newline | +| | `--help` | print command help | +| | `--version` | print version information | diff --git a/docs/Linux-Commands/.recycle/066-the-iptable-command.md b/docs/Linux-Commands/.recycle/066-the-iptable-command.md new file mode 100755 index 0000000..f5bd102 --- /dev/null +++ b/docs/Linux-Commands/.recycle/066-the-iptable-command.md @@ -0,0 +1,24 @@ +# The `iptables` Command + +The `iptables` command is used to set up and maintain tables for the Netfilter firewall for IPv4, included in the Linux kernel. The firewall matches packets with rules defined in these tables and then takes the specified action on a possible match. + +### Syntax: +``` +iptables --table TABLE -A/-C/-D... CHAIN rule --jump Target +``` + +### Example and Explanation: +*This command will append to the chain provided in parameters:* +``` +iptables [-t table] --append [chain] [parameters] +``` + +*This command drops all the traffic coming on any port:* +``` +iptables -t filter --append INPUT -j DROP +``` +### Flags and their Functionalities: +|Flag|Description| +|:---|:---| +|`-C`|Check if a rule is present in the chain or not. It returns 0 if the rule exists and returns 1 if it does not.| +|`-A`|Append to the chain provided in parameters.| \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/068-the-lsof-command.md b/docs/Linux-Commands/.recycle/068-the-lsof-command.md new file mode 100755 index 0000000..448b344 --- /dev/null +++ b/docs/Linux-Commands/.recycle/068-the-lsof-command.md @@ -0,0 +1,50 @@ +# The `lsof` command + +The `lsof` command shows **file infomation** of all the files opened by a running process. It's name is also derived from the fact that, list open files > `lsof` + +An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library , a stream or a network file (Internet socket, NFS file or UNIX domain socket). A specific file or all the files in a file system may be selected by path. +### Syntax: + +``` +lsof [-OPTION] [USER_NAME] +``` + +### Examples: + +1. To show all the files opened by all active processes: + +``` +lsof +``` + +2. To show the files opened by a particular user: + +``` +lsof -u [USER_NAME] +``` + + +3. To list the processes with opened files under a specified directory: + +``` +lsof +d [PATH_TO_DIR] +``` + +### Options and their Functionalities: + +|**Option** |**Additional Options** |**Description** | +|:---|:---|:---| +|`-i`|`tcp`/ `udp`/ `:port`|List all network connections running, Additionally, on udp/tcp or on specified port.| +|`-i4`|
-
|List all processes with ipv4 connections.| +|`-i6`|
-
|List all processes with ipv6 connections.| +|`-c`|`[PROCESS_NAME]`|List all the files of a particular process with given name.| +|`-p`|`[PROCESS_ID]`|List all the files opened by a specified process id.| +|`-p`|`^[PROCESS_ID]`|List all the files that are not opened by a specified process id.| +|`+d`|`[PATH]`|List the processes with opened files under a specified directory| +|`+R`|
-
|List the files opened by parent process Id.| + +### Help Command +Run below command to view the complete guide to `lsof` command. +``` +man lsof +``` diff --git a/docs/Linux-Commands/.recycle/069-the-bzip2-command.md b/docs/Linux-Commands/.recycle/069-the-bzip2-command.md new file mode 100755 index 0000000..29ab2bb --- /dev/null +++ b/docs/Linux-Commands/.recycle/069-the-bzip2-command.md @@ -0,0 +1,57 @@ +# The `bzip2` command + +The `bzip2` command lets you compress and decompress the files i.e. it helps in binding the files into a single file which takes less storage space as the original file use to take. + +### Syntax: + +``` +bzip2 [OPTIONS] filenames ... +``` + +#### Note : Each file is replaced by a compressed version of itself, with the name original name of the file followed by extension bz2. + +### Options and their Functionalities: + +|**Option** |**Alias** |**Description** | +|:---|:---|:---| +|`-d`|`--decompress`|to decompress compressed file| +|`-f`|`--force`|to force overwrite an existing output file| +|`-h`|`--help`|to display the help message and exit| +|`-k`|`--keep`|to enable file compression, doesn't deletes the original input file| +|`-L`|`--license`|to display the license terms and conditions| +|`-q`|`--quiet`|to suppress non-essential warning messages| +|`-t`|`--test`|to check integrity of the specified .bz2 file, but don't want to decompress them| +|`-v`|`--erbose`|to display details for each compression operation| +|`-V`|`--version`|to display the software version| +|`-z`|`--compress`|to enable file compression, but deletes the original input file| + + +> #### By default, when bzip2 compresses a file, it deletes the original (or input) file. However, if you don't want that to happen, use the -k command line option. + +### Examples: + +1. To force compression: +``` +bzip2 -z input.txt +``` +**Note: This option deletes the original file also** + +2. To force compression and also retain original input file: +``` +bzip2 -k input.txt +``` + +3. To force decompression: +``` +bzip2 -d input.txt.bz2 +``` + +4. To test integrity of compressed file: +``` +bzip2 -t input.txt.bz2 +``` + +5. To show the compression ratio for each file processed: +``` +bzip2 -v input.txt +``` diff --git a/docs/Linux-Commands/.recycle/070-the-service-command.md b/docs/Linux-Commands/.recycle/070-the-service-command.md new file mode 100755 index 0000000..c43e0f7 --- /dev/null +++ b/docs/Linux-Commands/.recycle/070-the-service-command.md @@ -0,0 +1,30 @@ +# The `service` command + +Service runs a System V init script in as predictable environment as possible, removing most environment variables and with current working directory set to /. + +The SCRIPT parameter specifies a System V init script, located in /etc/init.d/SCRIPT. The supported values of COMMAND depend on the invoked script, service passes COMMAND and OPTIONS it to the init script unmodified. All scripts should support at least the start and stop commands. As a special case, if COMMAND is --full-restart, the script is run twice, first with the stop command, then with the start command. + +The COMMAND can be at least start, stop, status, and restart. + +service --status-all runs all init scripts, in alphabetical order, with the `status` command + +Examples : + +1. To check the status of all the running services: + +``` +service --status-all +``` + +2. To run a script + +``` +service SCRIPT-Name start +``` + +3. A more generalized command: + +``` +service [SCRIPT] [COMMAND] [OPTIONS] + +``` \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/071-the-vmstat-command.md b/docs/Linux-Commands/.recycle/071-the-vmstat-command.md new file mode 100755 index 0000000..983452b --- /dev/null +++ b/docs/Linux-Commands/.recycle/071-the-vmstat-command.md @@ -0,0 +1,25 @@ +# The `vmstat` command + +The `vmstat` command lets you monitor the performance of your system. It shows you information about your memory, disk, processes, CPU scheduling, paging, and block IO. This command is also referred to as **virtual memory statistic report**. + +The very first report that is produced shows you the average details since the last reboot and after that, other reports are made which report over time. + +### `vmstat` + +![vmstat](https://imgur.com/9HZgBRN.png) + +As you can see it is a pretty useful little command. The most important things that we see above are the `free`, which shows us the free space that is not being used, `si` shows us how much memory is swapped in every second in kB, and `so` shows how much memory is swapped out each second in kB as well. + +### `vmstat -a` + +If we run `vmstat -a`, it will show us the active and inactive memory of the system running. + +![vmstat -a](https://imgur.com/LjL4tRh.png) + +### `vmstat -d` + +The `vmstat -d` command shows us all the disk statistics. + +![vmstat -d](https://imgur.com/y3L0pNN.png) + +As you can see this is a pretty useful little command that shows you different statistics about your virtual memory diff --git a/docs/Linux-Commands/.recycle/072-the-mpstat-command.md b/docs/Linux-Commands/.recycle/072-the-mpstat-command.md new file mode 100755 index 0000000..e13837e --- /dev/null +++ b/docs/Linux-Commands/.recycle/072-the-mpstat-command.md @@ -0,0 +1,57 @@ +# The `mpstat` command + +The `mpstat` command is used to report processor related statistics. It accurately displays the statistics of the CPU usage of the system and information about CPU utilization and performance. + +### Syntax: + +``` +mpstat [options] [ []] +``` + +#### Note : It initializes the first processor with CPU 0, the second one with CPU 1, and so on. + +### Options and their Functionalities: + +|**Option** |**Description** | +|-------------|----------------------------------------------------------------------| +|`-A` |to display all the detailed statistics | +|`-h` |to display mpstat help | +|`-I` |to display detailed interrupts statistics | +|`-n` |to report summary CPU statistics based on NUMA node placement | +|`-N` |to indicate the NUMA nodes for which statistics are to be reported | +|`-P` |to indicate the processors for which statistics are to be reported | +|`-o` |to display the statistics in JSON (Javascript Object Notation) format | +|`-T` |to display topology elements in the CPU report | +|`-u` |to report CPU utilization | +|`-v` |to display utilization statistics at the virtual processor level | +|`-V` |to display mpstat version | +|`-ALL` |to display detailed statistics about all CPUs | + + +### Examples: + +1. To display processor and CPU statistics: +``` +mpstat +``` + +2. To display processor number of all CPUs: +``` +mpstat -P ALL +``` + +3. To get all the information which the tool may collect: +``` +mpstat -A +``` + +4. To display CPU utilization by a specific processor: +``` +mpstat -P 0 +``` + +5. To display CPU usage with a time interval: +``` +mpstat 1 5 +``` +**Note: This command will print 5 reports with 1 second time interval** diff --git a/docs/Linux-Commands/.recycle/073-the-ncdu-command.md b/docs/Linux-Commands/.recycle/073-the-ncdu-command.md new file mode 100755 index 0000000..ee309b0 --- /dev/null +++ b/docs/Linux-Commands/.recycle/073-the-ncdu-command.md @@ -0,0 +1,36 @@ +# The `ncdu` Command + +`ncdu` (NCurses Disk Usage) is a curses-based version of the well-known `du` command. It provides a fast way to see what directories are using your disk space. + + +## Example +1. Quiet Mode +``` +ncdu -q +``` + +2. Omit mounted directories +``` +ncdu -q -x +``` + + + +## Syntax +``` +ncdu [-hqvx] [--exclude PATTERN] [-X FILE] dir +``` + + + + +## Additional Flags and their Functionalities: + +|Short Flag | Long Flag | Description| +|---|---|---| +| `-h`| - |Print a small help message| +| `-q`| - |Quiet mode. While calculating disk space, ncdu will update the screen 10 times a second by default, this will be decreased to once every 2 seconds in quiet mode. Use this feature to save bandwidth over remote connections.| +| `-v`| - |Print version.| +| `-x`| - |Only count files and directories on the same filesystem as the specified dir.| +| - | `--exclude PATTERN`|Exclude files that match PATTERN. This argument can be added multiple times to add more patterns.| +| `-X FILE`| `--exclude-from FILE`| Exclude files that match any pattern in FILE. Patterns should be separated by a newline.| diff --git a/docs/Linux-Commands/.recycle/074-the-uniq-command.md b/docs/Linux-Commands/.recycle/074-the-uniq-command.md new file mode 100755 index 0000000..935396d --- /dev/null +++ b/docs/Linux-Commands/.recycle/074-the-uniq-command.md @@ -0,0 +1,69 @@ +# The `uniq` command + +The `uniq` command in Linux is a command line utility that reports or filters out the repeated lines in a file. +In simple words, `uniq` is the tool that helps you to detect the adjacent duplicate lines and also deletes the duplicate lines. It filters out the adjacent matching lines from the input file(that is required as an argument) and writes the filtered data to the output file . + +### Examples: + +In order to omit the repeated lines from a file, the syntax would be the following: + +``` +uniq kt.txt +``` + +In order to tell the number of times a line was repeated, the syntax would be the following: + +``` +uniq -c kt.txt +``` + +In order to print repeated lines, the syntax would be the following: + +``` +uniq -d kt.txt +``` + +In order to print unique lines, the syntax would be the following: + +``` +uniq -u kt.txt +``` + +In order to allows the N fields to be skipped while comparing uniqueness of the lines, the syntax would be the following: + +``` +uniq -f 2 kt.txt +``` + +In order to allows the N characters to be skipped while comparing uniqueness of the lines, the syntax would be the following: + +``` +uniq -s 5 kt.txt +``` + +In order to to make the comparison case-insensitive, the syntax would be the following: + +``` +uniq -i kt.txt +``` + +### Syntax: + +``` +uniq [OPTION] [INPUT[OUTPUT]] +``` + +### Possible options: + +|**Flag** |**Description** |**Params** | +|:---|:---|:---| +|`-c`|It tells how many times a line was repeated by displaying a number as a prefix with the line.|-| +|`-d`|It only prints the repeated lines and not the lines which aren’t repeated.|-| +|`-i`|By default, comparisons done are case sensitive but with this option case insensitive comparisons can be made.|-| +|`-f`|It allows you to skip N fields(a field is a group of characters, delimited by whitespace) of a line before determining uniqueness of a line.|N| +|`-s`|It doesn’t compares the first N characters of each line while determining uniqueness. This is like the -f option, but it skips individual characters rather than fields.|N| +|`-u`|It allows you to print only unique lines.|-| +|`-z`|It will make a line end with 0 byte(NULL), instead of a newline.|-| +|`-w`|It only compares N characters in a line.|N| +|`--help`|It displays a help message and exit.|-| +|`--version`|It displays version information and exit.|-| diff --git a/docs/Linux-Commands/.recycle/075-the-rpm-command.md b/docs/Linux-Commands/.recycle/075-the-rpm-command.md new file mode 100755 index 0000000..54877f3 --- /dev/null +++ b/docs/Linux-Commands/.recycle/075-the-rpm-command.md @@ -0,0 +1,103 @@ +# The `RPM` command + +`rpm` - RPM Package Manager + +`rpm` is a powerful __Package Manager__, which can be used to build, install, query, verify, update, and erase individual software packages. A __package__ consists of an archive of files and meta-data used to install and erase the archive files. The meta-data includes helper scripts, file attributes, and descriptive information about the package. Packages come in two varieties: binary packages, used to encapsulate software to be installed, and source packages, containing the source code and recipe necessary to produce binary packages. + +One of the following basic modes must be selected: __Query, Verify, Signature Check, Install/Upgrade/Freshen, Uninstall, Initialize Database, Rebuild Database, Resign, Add Signature, Set Owners/Groups, Show Querytags, and Show Configuration.__ + +**General Options** + +These options can be used in all the different modes. + +|Short Flag| Long Flag| Description| +|---|---|---| +| -? | --help| Print a longer usage message then normal.| +| - |--version |Print a single line containing the version number of rpm being used.| +| - | --quiet | Print as little as possible - normally only error messages will be displayed.| +| -v | - | Print verbose information - normally routine progress messages will be displayed.| +| -vv | - | Print lots of ugly debugging information.| +| - | --rcfile FILELIST | Each of the files in the colon separated FILELIST is read sequentially by rpm for configuration information. Only the first file in the list must exist, and tildes will be expanded to the value of $HOME. The default FILELIST is /usr/lib/rpm/rpmrc:/usr/lib/rpm/redhat/rpmrc:/etc/rpmrc:~/.rpmrc. | +| - | --pipe CMD | Pipes the output of rpm to the command CMD. | +| - | --dbpath DIRECTORY | Use the database in DIRECTORY rather than the default path /var/lib/rpm | +| - | --root DIRECTORY | Use the file system tree rooted at DIRECTORY for all operations. Note that this means the database within DIRECTORY will be used for dependency checks and any scriptlet(s) (e.g. %post if installing, or %prep if building, a package) will be run after a chroot(2) to DIRECTORY. | +| -D | --define='MACRO EXPR' | Defines MACRO with value EXPR.| +| -E | --eval='EXPR' | Prints macro expansion of EXPR. | + + +# Synopsis + +## Querying and Verifying Packages: + +``` +rpm {-q|--query} [select-options] [query-options] + +rpm {-V|--verify} [select-options] [verify-options] + +rpm --import PUBKEY ... + +rpm {-K|--checksig} [--nosignature] [--nodigest] PACKAGE_FILE ... +``` + +## Installing, Upgrading, and Removing Packages: + +``` +rpm {-i|--install} [install-options] PACKAGE_FILE ... + +rpm {-U|--upgrade} [install-options] PACKAGE_FILE ... + +rpm {-F|--freshen} [install-options] PACKAGE_FILE ... + +rpm {-e|--erase} [--allmatches] [--nodeps] [--noscripts] [--notriggers] [--test] PACKAGE_NAME ... +``` + +## Miscellaneous: + +``` +rpm {--initdb|--rebuilddb} + +rpm {--addsign|--resign} PACKAGE_FILE... + +rpm {--querytags|--showrc} + +rpm {--setperms|--setugids} PACKAGE_NAME . + +``` + + + + +### query-options + +``` +[--changelog] [-c,--configfiles] [-d,--docfiles] [--dump] +[--filesbypkg] [-i,--info] [--last] [-l,--list] +[--provides] [--qf,--queryformat QUERYFMT] +[-R,--requires] [--scripts] [-s,--state] +[--triggers,--triggerscripts] +``` + +### verify-options + +``` +[--nodeps] [--nofiles] [--noscripts] +[--nodigest] [--nosignature] +[--nolinkto] [--nofiledigest] [--nosize] [--nouser] +[--nogroup] [--nomtime] [--nomode] [--nordev] +[--nocaps] +``` +### install-options +``` +[--aid] [--allfiles] [--badreloc] [--excludepath OLDPATH] +[--excludedocs] [--force] [-h,--hash] +[--ignoresize] [--ignorearch] [--ignoreos] +[--includedocs] [--justdb] [--nodeps] +[--nodigest] [--nosignature] [--nosuggest] +[--noorder] [--noscripts] [--notriggers] +[--oldpackage] [--percent] [--prefix NEWPATH] +[--relocate OLDPATH=NEWPATH] +[--replacefiles] [--replacepkgs] +[--test] +``` + + diff --git a/docs/Linux-Commands/.recycle/076-the-scp-command.md b/docs/Linux-Commands/.recycle/076-the-scp-command.md new file mode 100755 index 0000000..24ef15b --- /dev/null +++ b/docs/Linux-Commands/.recycle/076-the-scp-command.md @@ -0,0 +1,69 @@ +# The `scp` command + +SCP (secure copy) is a command-line utility that allows you to securely copy files and directories between two locations. + +Both the files and passwords are encrypted so that anyone snooping on the traffic doesn't get anything sensitive. + +### Different ways to copy a file or directory: + +- From local system to a remote system. +- From a remote system to a local system. +- Between two remote systems from the local system. + +### Examples: + +1. To copy the files from a local system to a remote system: + +``` +scp /home/documents/local-file root@{remote-ip-address}:/home/ +``` + +2. To copy the files from a remote system to the local system: +``` +scp root@{remote-ip-address}:/home/remote-file /home/documents/ +``` + +3. To copy the files between two remote systems from the local system. +``` +scp root@{remote1-ip-address}:/home/remote-file root@{remote2-ip-address}/home/ +``` +4. To copy file though a jump host server. +``` +scp /home/documents/local-file -oProxyJump= root@{remote-ip-address}/home/ +``` +On newer version of scp on some machines you can use the above command with a `-J` flag. +``` +scp /home/documents/local-file -J root@{remote-ip-address}/home/ +``` + +### Syntax: +``` +scp [OPTION] [user@]SRC_HOST:]file1 [user@]DEST_HOST:]file2 +``` +- `OPTION` - scp options such as cipher, ssh configuration, ssh port, limit, recursive copy …etc. +- `[user@]SRC_HOST:]file1` - Source file +- `[user@]DEST_HOST:]file2` - Destination file + +Local files should be specified using an absolute or relative path, while remote file names should include a user and host specification. + +scp provides several that control every aspect of its behaviour. The most widely used options are: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-P`|
-
|Specifies the remote host ssh port.| +|`-p`|
-
|Preserves files modification and access times.| +|`-q`|
-
|Use this option if you want to suppress the progress meter and non-error messages.| +|`-C`|
-
|This option forces scp to compresses the data as it is sent to the destination machine.| +|`-r`|
-
|This option tells scp to copy directories recursively.| + +### Before you begin + +The `scp` command relies on `ssh` for data transfer, so it requires an `ssh key` or `password` to authenticate on the remote systems. + +The `colon (:)` is how scp distinguish between local and remote locations. + +To be able to copy files, you must have at least read permissions on the source file and write permission on the target system. + +Be careful when copying files that share the same name and location on both systems, `scp` will overwrite files without warning. + +When transferring large files, it is recommended to run the scp command inside a `screen` or `tmux` session. diff --git a/docs/Linux-Commands/.recycle/078-the-split-command.md b/docs/Linux-Commands/.recycle/078-the-split-command.md new file mode 100755 index 0000000..58a194c --- /dev/null +++ b/docs/Linux-Commands/.recycle/078-the-split-command.md @@ -0,0 +1,76 @@ +# The `split` command + +The `split` command in Linux is used to split a file into smaller files. + +### Examples + +1. Split a file into a smaller file using file name + +``` +split filename.txt +``` + +2. Split a file named filename into segments of 200 lines beginning with prefix file + +``` +split -l 200 filename file +``` + +This will create files of the name fileaa, fileab, fileac, filead, etc. of 200 lines. + +3. Split a file named filename into segments of 40 bytes with prefix file + +``` +split -b 40 filename file +``` + +This will create files of the name fileaa, fileab, fileac, filead, etc. of 40 bytes. + +4. Split a file using --verbose to see the files being created. + +``` +split filename.txt --verbose +``` + +### Syntax: + +``` +split [options] filename [prefix] +``` + +### Additional Flags and their Functionalities + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-a`|`--suffix-length=N`|Generate suffixes of length N (default 2)| +||`--additional-suffix=SUFFIX`|Append an additional SUFFIX to file names| +|`-b`|`--bytes=SIZE`|Put SIZE bytes per output file| +|`-C`|`--line-bytes=SIZE`|Put at most SIZE bytes of records per output file| +|`-d`| |Use numeric suffixes starting at 0, not alphabetic| +||`--numeric-suffixes[=FROM]`|Same as -d, but allow setting the start value| +|`-x`||Use hex suffixes starting at 0, not alphabetic| +||`--hex-suffixes[=FROM]`|Same as -x, but allow setting the start value| +|`-e`|`--elide-empty-files`|Do not generate empty output files with '-n'| +||`--filter=COMMAND`|Write to shell COMMAND;
file name is $FILE| +|`-l`|`--lines=NUMBER`|Put NUMBER lines/records per output file| +|`-n`|`--number=CHUNKS`|Generate CHUNKS output files;
see explanation below| +|`-t`|`--separator=SEP`|Use SEP instead of newline as the record separator;
'\0' (zero) specifies the NUL character| +|`-u`|`--unbuffered`|Immediately copy input to output with '-n r/...'| +||`--verbose`|Print a diagnostic just before each
output file is opened| +||`--help`|Display this help and exit| +||`--version`|Output version information and exit| + +The SIZE argument is an integer and optional unit (example: 10K is 10*1024). +Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000). + +CHUNKS may be: +|**CHUNKS** |**Description** | +|:---|:---| +|`N`|Split into N files based on size of input| +|`K/N`|Output Kth of N to stdout| +|`l/N`|Split into N files without splitting lines/records| +|`l/K/N`|Output Kth of N to stdout without splitting lines/records| +|`r/N`|Like 'l' but use round robin distribution| +|`r/K/N`|Likewise but only output Kth of N to stdout| + + diff --git a/docs/Linux-Commands/.recycle/079-the-stat-command.md b/docs/Linux-Commands/.recycle/079-the-stat-command.md new file mode 100755 index 0000000..90465ad --- /dev/null +++ b/docs/Linux-Commands/.recycle/079-the-stat-command.md @@ -0,0 +1,61 @@ +# The `stat` command + +The `stat` command lets you display file or file system status. It gives you useful information about the file (or directory) on which you use it. + +### Examples: + +1. Basic command usage + +``` +stat file.txt +``` + +2. Use the `-c` (or `--format`) argument to only display information you want to see (here, the total size, in bytes) + +``` +stat file.txt -c %s +``` + +### Syntax: + +``` +stat [OPTION] [FILE] +``` + +### Additional Flags and their Functionalities: + +| Short Flag | Long Flag | Description | +| ---------- | ----------------- | ----------------------------------------------------------------------------- | +| `-L` | `--dereference` | Follow links | +| `-f` | `--file-system` | Display file system status instead of file status | +| `-c` | `--format=FORMAT` | Specify the format (see below) | +| `-t` | `--terse` | Print the information in terse form | +| - | `--cached=MODE` | Specify how to use cached attributes. Can be: `always`, `never`, or `default` | +| - | `--printf=FORMAT` | Like `--format`, but interpret backslash escapes (`\n`, `\t`, ...) | +| - | `--help` | Display the help and exit | +| - | `--version` | Output version information and exit | + + +### Example of Valid Format Sequences for Files: + +| Format | Description | +| ------ | ---------------------------------------------------- | +| `%a` | Permission bits in octal | +| `%A` | Permission bits and file type in human readable form | +| `%d` | Device number in decimal | +| `%D` | Device number in hex | +| `%F` | File type | +| `%g` | Group ID of owner | +| `%G` | Group name of owner | +| `%h` | Number of hard links | +| `%i` | Inode number | +| `%m` | Mount point | +| `%n` | File name | +| `%N` | Quoted file name with dereference if symbolic link | +| `%s` | Total size, in bytes | +| `%u` | User ID of owner | +| `%U` | User name of owner | +| `%w` | Time of file birth, human-readable; - if unknown | +| `%x` | Time of last access, human-readable | +| `%y` | Time of last data modification, human-readable | +| `%z` | Time of last status change, human-readable | diff --git a/docs/Linux-Commands/.recycle/083-the-ionice-command.md b/docs/Linux-Commands/.recycle/083-the-ionice-command.md new file mode 100755 index 0000000..e6ec1dc --- /dev/null +++ b/docs/Linux-Commands/.recycle/083-the-ionice-command.md @@ -0,0 +1,93 @@ +# The `ionice` command + +The `ionice` command is used to set or get process I/O scheduling class and priority. + +If no arguments are given , `ionice` will query the current I/O scheduling class and priority for that process. + +## Usage + + ``` +ionice [options] -p +``` + +``` +ionice [options] -P +``` + +``` +ionice [options] -u +``` + +``` +ionice [options] +``` + +## A process can be of three scheduling classes: +- ### Idle + + A program with idle I/O priority will only get disk time when `no other program has asked for disk I/O for a defined grace period`. + + The impact of idle processes on normal system actively should be `zero`. + + This scheduling class `doesn’t take priority` argument. + + Presently this scheduling class is permitted for an `ordinary user (since kernel 2.6.25)`. +- ### Best Effort + + This is `effective` scheduling class for any process that has `not asked for a specific I/O priority`. + + This class `takes priority argument from 0-7`, with `lower` number being `higher priority`. + + Programs running at the same best effort priority are served in `round- robbin fashion`. + + Note that before kernel 2.6.26 a process that has not asked for an I/O priority formally uses “None” as scheduling class , but the io schedular will treat such processes as if it were in the best effort class. + + The priority within best effort class will be dynamically derived form the CPU nice level of the process : io_priority = ( cpu_nice + 20 ) / 5/ + for kernels after 2.6.26 with CFQ I/O schedular a process that has not asked for sn io priority inherits CPU scheduling class. + + `The I/O priority is derived from the CPU nice level of the process` ( smr sd before kernel 2.6.26 ). + +- ### Real Time + + The real time schedular class is `given first access to disk, regardless of what else is going on in the system`. + + Thus the real time class needs to be used with some care, as it cans tarve other processes . + + As with the best effort class, `8 priority levels are defined denoting how big a time slice a given process will receive on each scheduling window`. + + This scheduling class is `not permitted for an ordinary user(non-root)`. + +## Options +| Options | Description | +|---|---| +| -c, --class | name or number of scheduling class, 0: none, 1: realtime, 2: best-effort, 3: idle| +| -n, --classdata | priority (0..7) in the specified scheduling class,only for the realtime and best-effort classes| +| -p, --pid ... | act on these already running processes| +| -P, --pgid ... | act on already running processes in these groups| +| -t, --ignore | ignore failures| +| -u, --uid ... | act on already running processes owned by these users| +| -h, --help | display this help| +| -V, --version | display version| + +For more details see ionice(1). + + +## Examples +| Command | O/P |Explanation| +|---|---|---| +|`$ ionice` |*none: prio 4*|Running alone `ionice` will give the class and priority of current process | +|`$ ionice -p 101`|*none : prio 4*|Give the details(*class : priority*) of the process specified by given process id| +|`$ ionice -p 2` |*none: prio 4*| Check the class and priority of process with pid 2 it is none and 4 resp.| +|`$ ionice -c2 -n0 -p2`|2 ( best-effort ) priority 0 process 2 | Now lets set process(pid) 2 as a best-effort program with highest priority| +|$ `ionice` -p 2|best-effort : prio 0| Now if I check details of Process 2 you can see the updated one| +|$ `ionice` /bin/ls||get priority and class info of bin/ls | +|$ `ionice` -n4 -p2||set priority 4 of process with pid 2 | +|$ `ionice` -p 2| best-effort: prio 4| Now observe the difference between the command ran above and this one we have changed priority from 0 to 4| +|$ `ionice` -c0 -n4 -p2|ionice: ignoring given class data for none class|(Note that before kernel 2.6.26 a process that has not asked for an I/O priority formally uses “None” as scheduling class , | +|||but the io schedular will treat such processes as if it were in the best effort class. )| +|||-t option : ignore failure| +|$ `ionice` -c0 -n4 -p2 -t| | For ignoring the warning shown above we can use -t option so it will ignore failure | + +## Conclusion + + Thus we have successfully learnt about `ionice` command. diff --git a/docs/Linux-Commands/.recycle/086-the-rsync-command.md b/docs/Linux-Commands/.recycle/086-the-rsync-command.md new file mode 100755 index 0000000..6ed654f --- /dev/null +++ b/docs/Linux-Commands/.recycle/086-the-rsync-command.md @@ -0,0 +1,85 @@ +# The `rsync` command + +The `rsync` command is probably one of the most used commands out there. It is used to securely copy files from one server to another over SSH. + +Compared to the `scp` command, which does a similar thing, `rsync` makes the transfer a lot faster, and in case of an interruption, you could restore/resume the transfer process. + +In this tutorial, I will show you how to use the `rsync` command and copy files from one server to another and also share a few useful tips! + +Before you get started, you would need to have 2 Linux servers. I will be using DigitalOcean for the demo and deploy 2 Ubuntu servers. + +You can use my referral link to get a free $100 credit that you could use to deploy your virtual machines and test the guide yourself on a few DigitalOcean servers: + +**[DigitalOcean $100 Free Credit](https://m.do.co/c/2a9bba940f39)** + +## Transfer Files from local server to remote + +This is one of the most common causes. Essentially this is how you would copy the files from the server that you are currently on (the source server) to remote/destination server. + +What you need to do is SSH to the server that is holding your files, cd to the directory that you would like to transfer over: + +``` +cd /var/www/html +``` + +And then run: + +``` +rsync -avz user@your-remote-server.com:/home/user/dir/ +``` + +The above command would copy all the files and directories from the current folder on your server to your remote server. + +Rundown of the command: + +* `-a`: is used to specify that you want recursion and want to preserve the file permissions and etc. +* `-v`: is verbose mode, it increases the amount of information you are given during the transfer. +* `-z`: this option, rsync compresses the file data as it is sent to the destination machine, which reduces the amount of data being transmitted -- something that is useful over a slow connection. + +I recommend having a look at the following website which explains the commands and the arguments very nicely: + +[https://explainshell.com/explain?cmd=rsync+-avz](https://explainshell.com/explain?cmd=rsync+-avz) + +In case that the SSH service on the remote server is not running on the standard `22` port, you could use `rsync` with a special SSH port: + +``` +rsync -avz -e 'ssh -p 1234' user@your-remote-server.com:/home/user/dir/ +``` + +## Transfer Files remote server to local + +In some cases you might want to transfer files from your remote server to your local server, in this case, you would need to use the following syntax: + +``` +rsync -avz your-user@your-remote-server.com:/home/user/dir/ /home/user/local-dir/ +``` + +Again, in case that you have a non-standard SSH port, you can use the following command: + +``` +rsync -avz -e 'ssh -p 2510' your-user@your-remote-server.com:/home/user/dir/ /home/user/local-dir/ +``` + +## Transfer only missing files + +If you would like to transfer only the missing files you could use the `--ignore-existing` flag. + +This is very useful for final sync in order to ensure that there are no missing files after a website or a server migration. + +Basically the commands would be the same apart from the appended --ignore-existing flag: + +``` + rsync -avz --ignore-existing user@your-remote-server.com:/home/user/dir/ +``` + +## Conclusion + +Using `rsync` is a great way to quickly transfer some files from one machine over to another in a secure way over SSH. + +For more cool Linux networking tools, I would recommend checking out this tutorial here: + +[Top 15 Linux Networking tools that you should know!](https://devdojo.com/serverenthusiast/top-15-linux-networking-tools-that-you-should-know) + +Hope that this helps! + +Initially posted here: [How to Transfer Files from One Linux Server to Another Using rsync](https://devdojo.com/bobbyiliev/how-to-transfer-files-from-one-linux-server-to-another-using-rsync) diff --git a/docs/Linux-Commands/.recycle/087-the-dig-command.md b/docs/Linux-Commands/.recycle/087-the-dig-command.md new file mode 100755 index 0000000..c749611 --- /dev/null +++ b/docs/Linux-Commands/.recycle/087-the-dig-command.md @@ -0,0 +1,133 @@ +# The `dig` command + +dig - DNS lookup utility + +The `dig` is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that + were queried. + +### Examples: + +1. Dig is a network administration command-line tool for querying the Domain Name System. + +``` +dig google.com +``` + +2. The system will list all google.com DNS records that it finds, along with the IP addresses. + +``` +dig google.com ANY +``` + +### Syntax: + +``` +dig [server] [name] [type] [q-type] [q-class] {q-opt} + {global-d-opt} host [@local-server] {local-d-opt} + [ host [@local-server] {local-d-opt} [...]] +``` + + +### Additional Flags and their Functionalities: + +```bash + +domain is in the Domain Name System + q-class is one of (in,hs,ch,...) [default: in] + q-type is one of (a,any,mx,ns,soa,hinfo,axfr,txt,...) [default:a] + (Use ixfr=version for type ixfr) + q-opt is one of: + -4 (use IPv4 query transport only) + -6 (use IPv6 query transport only) + -b address[#port] (bind to source address/port) + -c class (specify query class) + -f filename (batch mode) + -k keyfile (specify tsig key file) + -m (enable memory usage debugging) + -p port (specify port number) + -q name (specify query name) + -r (do not read ~/.digrc) + -t type (specify query type) + -u (display times in usec instead of msec) + -x dot-notation (shortcut for reverse lookups) + -y [hmac:]name:key (specify named base64 tsig key) + d-opt is of the form +keyword[=value], where keyword is: + +[no]aaflag (Set AA flag in query (+[no]aaflag)) + +[no]aaonly (Set AA flag in query (+[no]aaflag)) + +[no]additional (Control display of additional section) + +[no]adflag (Set AD flag in query (default on)) + +[no]all (Set or clear all display flags) + +[no]answer (Control display of answer section) + +[no]authority (Control display of authority section) + +[no]badcookie (Retry BADCOOKIE responses) + +[no]besteffort (Try to parse even illegal messages) + +bufsize[=###] (Set EDNS0 Max UDP packet size) + +[no]cdflag (Set checking disabled flag in query) + +[no]class (Control display of class in records) + +[no]cmd (Control display of command line - + global option) + +[no]comments (Control display of packet header + and section name comments) + +[no]cookie (Add a COOKIE option to the request) + +[no]crypto (Control display of cryptographic + fields in records) + +[no]defname (Use search list (+[no]search)) + +[no]dnssec (Request DNSSEC records) + +domain=### (Set default domainname) + +[no]dscp[=###] (Set the DSCP value to ### [0..63]) + +[no]edns[=###] (Set EDNS version) [0] + +ednsflags=### (Set EDNS flag bits) + +[no]ednsnegotiation (Set EDNS version negotiation) + +ednsopt=###[:value] (Send specified EDNS option) + +noednsopt (Clear list of +ednsopt options) + +[no]expandaaaa (Expand AAAA records) + +[no]expire (Request time to expire) + +[no]fail (Don't try next server on SERVFAIL) + +[no]header-only (Send query without a question section) + +[no]identify (ID responders in short answers) + +[no]idnin (Parse IDN names [default=on on tty]) + +[no]idnout (Convert IDN response [default=on on tty]) + +[no]ignore (Don't revert to TCP for TC responses.) + +[no]keepalive (Request EDNS TCP keepalive) + +[no]keepopen (Keep the TCP socket open between queries) + +[no]mapped (Allow mapped IPv4 over IPv6) + +[no]multiline (Print records in an expanded format) + +ndots=### (Set search NDOTS value) + +[no]nsid (Request Name Server ID) + +[no]nssearch (Search all authoritative nameservers) + +[no]onesoa (AXFR prints only one soa record) + +[no]opcode=### (Set the opcode of the request) + +padding=### (Set padding block size [0]) + +[no]qr (Print question before sending) + +[no]question (Control display of question section) + +[no]raflag (Set RA flag in query (+[no]raflag)) + +[no]rdflag (Recursive mode (+[no]recurse)) + +[no]recurse (Recursive mode (+[no]rdflag)) + +retry=### (Set number of UDP retries) [2] + +[no]rrcomments (Control display of per-record comments) + +[no]search (Set whether to use searchlist) + +[no]short (Display nothing except short + form of answers - global option) + +[no]showsearch (Search with intermediate results) + +[no]split=## (Split hex/base64 fields into chunks) + +[no]stats (Control display of statistics) + +subnet=addr (Set edns-client-subnet option) + +[no]tcflag (Set TC flag in query (+[no]tcflag)) + +[no]tcp (TCP mode (+[no]vc)) + +timeout=### (Set query timeout) [5] + +[no]trace (Trace delegation down from root [+dnssec]) + +tries=### (Set number of UDP attempts) [3] + +[no]ttlid (Control display of ttls in records) + +[no]ttlunits (Display TTLs in human-readable units) + +[no]unexpected (Print replies from unexpected sources + default=off) + +[no]unknownformat (Print RDATA in RFC 3597 "unknown" format) + +[no]vc (TCP mode (+[no]tcp)) + +[no]yaml (Present the results as YAML) + +[no]zflag (Set Z flag in query) + global d-opts and servers (before host name) affect all queries. + local d-opts and servers (after host name) affect only that lookup. + -h (print help and exit) + -v (print version and exit) + +``` diff --git a/docs/Linux-Commands/.recycle/088-the-whois-command.md b/docs/Linux-Commands/.recycle/088-the-whois-command.md new file mode 100755 index 0000000..c8470b3 --- /dev/null +++ b/docs/Linux-Commands/.recycle/088-the-whois-command.md @@ -0,0 +1,66 @@ +# The `whois` command + +The `whois` command in Linux to find out information about a domain, such as the owner of the domain, the owner’s contact information, and the nameservers that the domain is using. + +### Examples: + +1. Performs a whois query for the domain name: + +``` +whois {Domain_name} +``` + +2. -H option omits the lengthy legal disclaimers that many domain registries deliver along with the domain information. + +``` +whois -H {Domain_name} +``` + +### Syntax: + +``` +whois [ -h HOST ] [ -p PORT ] [ -aCFHlLMmrRSVx ] [ -g SOURCE:FIRST-LAST ] + [ -i ATTR ] [ -S SOURCE ] [ -T TYPE ] object +``` +``` +whois -t TYPE +``` +``` +whois -v TYPE +``` +``` +whois -q keyword +``` + + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-h HOST`, `--host HOST`|Connect to HOST.| +|`-H`|Do not display the legal disclaimers some registries like to show you.| +|`-p`, `--port PORT`|Connect to PORT.| +|`--verbose`|Be verbose.| +|`--help`|Display online help.| +|`--version`|Display client version information. Other options are flags understood by whois.ripe.net and some other RIPE-like servers.| +|`-a`|Also search all the mirrored databases.| +|`-b`|Return brief IP address ranges with abuse contact.| +|`-B`|Disable object filtering *(show the e-mail addresses)*| +|`-c`|Return the smallest IP address range with a reference to an irt object.| +|`-d`|Return the reverse DNS delegation object too.| +|`-g SOURCE:FIRST-LAST`|Search updates from SOURCE database between FIRST and LAST update serial number. It's useful to obtain Near Real Time Mirroring stream.| +|`-G`|Disable grouping of associated objects.| +|`-i ATTR[,ATTR]...`|Search objects having associated attributes. ATTR is attribute name. Attribute value is positional OBJECT argument.| +|`-K`|Return primary key attributes only. Exception is members attribute of set object which is always returned. Another exceptions are all attributes of objects organisation, person, and role that are never returned.| +|`-l`|Return the one level less specific object.| +|`-L`|Return all levels of less specific objects.| +|`-m`|Return all one level more specific objects.| +|`-M`|Return all levels of more specific objects.| +|`-q KEYWORD`|Return list of keywords supported by server. KEYWORD can be version for server version, sources for list of source databases, or types for object types.| +|`-r`|Disable recursive look-up for contact information.| +|`-R`|Disable following referrals and force showing the object from the local copy in the server.| +|`-s SOURCE[,SOURCE]...`|Request the server to search for objects mirrored from SOURCES. Sources are delimited by comma and the order is significant. Use `-q` sources option to obtain list of valid sources.| +|`-t TYPE`|Return the template for a object of TYPE.| +|`-T TYPE[,TYPE]...`|Restrict the search to objects of TYPE. Multiple types are separated by a comma.| +|`-v TYPE`|Return the verbose template for a object of TYPE.| +|`-x`|Search for only exact match on network address prefix.| diff --git a/docs/Linux-Commands/.recycle/090-the-awk-command.md b/docs/Linux-Commands/.recycle/090-the-awk-command.md new file mode 100755 index 0000000..3367c54 --- /dev/null +++ b/docs/Linux-Commands/.recycle/090-the-awk-command.md @@ -0,0 +1,90 @@ +# The `awk` command + +Awk is a general-purpose scripting language designed for advanced text processing. It is mostly used as a reporting and analysis tool. + +#### WHAT CAN WE DO WITH AWK? + +1. AWK Operations: +(a) Scans a file line by line +(b) Splits each input line into fields +(c) Compares input line/fields to pattern +(d) Performs action(s) on matched lines + + + +2. Useful For: +(a) Transform data files +(b) Produce formatted reports + +3. Programming Constructs: +(a) Format output lines +(b) Arithmetic and string operations +(c) Conditionals and loops + +#### Syntax + +``` +awk options 'selection _criteria {action }' input-file > output-file +``` + +#### Example +Consider the following text file as the input file for below example: + + ``` + $cat > employee.txt + ``` + ``` + ajay manager account 45000 + sunil clerk account 25000 + varun manager sales 50000 + amit manager account 47000 + tarun peon sales 15000 + ``` + +1. Default behavior of Awk: By default Awk prints every line of data from the specified file. +``` +$ awk '{print}' employee.txt +``` +``` +ajay manager account 45000 +sunil clerk account 25000 +varun manager sales 50000 +amit manager account 47000 +tarun peon sales 15000 +``` +In the above example, no pattern is given. So the actions are applicable to all the lines. Action print without any argument prints the whole line by default, so it prints all the lines of the file without failure. + +2. Print the lines which match the given pattern. +``` +awk '/manager/ {print}' employee.txt +``` +``` +ajay manager account 45000 +varun manager sales 50000 +amit manager account 47000 +``` +In the above example, the awk command prints all the line which matches with the ‘manager’. + +3. Splitting a Line Into Fields : For each record i.e line, the awk command splits the record delimited by whitespace character by default and stores it in the $n variables. If the line has 4 words, it will be stored in $1, $2, $3 and $4 respectively. Also, $0 represents the whole line. +``` +$ awk '{print $1,$4}' employee.txt +``` +``` +ajay 45000 +sunil 25000 +varun 50000 +amit 47000 +tarun 15000 +``` + +#### Built-In Variables In Awk + +Awk’s built-in variables include the field variables—$1, $2, $3, and so on ($0 is the entire line) — that break a line of text into individual words or pieces called fields. + + +NR: NR command keeps a current count of the number of input records. Remember that records are usually lines. Awk command performs the pattern/action statements once for each record in a file. +NF: NF command keeps a count of the number of fields within the current input record. +FS: FS command contains the field separator character which is used to divide fields on the input line. The default is “white space”, meaning space and tab characters. FS can be reassigned to another character (typically in BEGIN) to change the field separator. +RS: RS command stores the current record separator character. Since, by default, an input line is the input record, the default record separator character is a newline. +OFS: OFS command stores the output field separator, which separates the fields when Awk prints them. The default is a blank space. Whenever print has several parameters separated with commas, it will print the value of OFS in between each parameter. +ORS: ORS command stores the output record separator, which separates the output lines when Awk prints them. The default is a newline character. print automatically outputs the contents of ORS at the end of whatever it is given to print. \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/094-the-pstree-command.md b/docs/Linux-Commands/.recycle/094-the-pstree-command.md new file mode 100755 index 0000000..78cfd19 --- /dev/null +++ b/docs/Linux-Commands/.recycle/094-the-pstree-command.md @@ -0,0 +1,69 @@ + +# The `pstree` command + +The `pstree` command is similar to `ps`, but instead of listing the running processes, it shows them as a tree. The tree-like format is sometimes more suitable way to display the processes hierarchy which is a much simpler way to visualize running processes. The root of the tree is either init or the process with the given pid. + +### Examples + +1. To display a hierarchical tree structure of all running processes: + +``` +pstree +``` + +2. To display a tree with the given process as the root of the tree: + +``` +pstree [pid] +``` + +3. To show only those processes that have been started by a user: + +``` +pstree [USER] +``` + +4. To show the parent processes of the given process: + +``` +pstree -s [PID] +``` + +5. To view the output one page at a time, pipe it to the `less` command: + +``` +pstree | less +``` + + +### Syntax + +`ps [OPTIONS] [USER or PID]` + + +### Additional Flags and their Functionalities + + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-a`|`--arguments`|Show command line arguments| +|`-A`|`--ascii`|use ASCII line drawing characters| +|`-c`|`--compact`|Don't compact identical subtrees| +|`-h`|`--highlight-all`|Highlight current process and its ancestors| +|`-H PID`|`--highlight-pid=PID`|highlight this process and its ancestors| +|`-g`|`--show-pgids`|show process group ids; implies `-c`| +|`-G`|`--vt100`|use VT100 line drawing characters| +|`-l`|`--long`|Don't truncate long lines| +|`-n`|`--numeric-sort`|Sort output by PID| +|`-N type`|`--ns-sort=type`|Sort by namespace type (cgroup, ipc, mnt, net, pid, user, uts)| +|`-p`|`--show-pids`|show PIDs; implies -c| +|`-s`|`--show-parents`|Show parents of the selected process| +|`-S`|`--ns-changes`|show namespace transitions| +|`-t`|`--thread-names`|Show full thread names| +|`-T`|`--hide-threads`|Hide threads, show only processes| +|`-u`|`--uid-changes`|Show uid transitions| +|`-U`|`--unicode`|Use UTF-8 (Unicode) line drawing characters| +|`-V`|`--version`|Display version information| +|`-Z`|`--security-context`|Show SELinux security contexts| + + diff --git a/docs/Linux-Commands/.recycle/095-the-tree-command.md b/docs/Linux-Commands/.recycle/095-the-tree-command.md new file mode 100755 index 0000000..37a3d6d --- /dev/null +++ b/docs/Linux-Commands/.recycle/095-the-tree-command.md @@ -0,0 +1,46 @@ +# The `tree` command + +The `tree` command in Linux recursively lists directories as tree structures. Each listing is indented according to its depth relative to root of the tree. + +### Examples: + +1. Show a tree representation of the current directory. + +``` +tree +``` + +2. -L NUMBER limits the depth of recursion to avoid display very deep trees. + +``` +tree -L 2 / +``` + +### Syntax: + +``` +tree [-acdfghilnpqrstuvxACDFQNSUX] [-L level [-R]] [-H baseHREF] [-T title] + [-o filename] [--nolinks] [-P pattern] [-I pattern] [--inodes] + [--device] [--noreport] [--dirsfirst] [--version] [--help] [--filelimit #] + [--si] [--prune] [--du] [--timefmt format] [--matchdirs] [--from-file] + [--] [directory ...] +``` + + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-a`|Print all files, including hidden ones.| +|`-d`|Only list directories.| +|`-l`|Follow symbolic links into directories.| +|`-f`|Print the full path to each listing, not just its basename.| +|`-x`|Do not move across file-systems.| +|`-L #`|Limit recursion depth to #.| +|`-P REGEX`|Recurse, but only list files that match the REGEX.| +|`-I REGEX`|Recurse, but do not list files that match the REGEX.| +|`--ignore-case`|Ignore case while pattern-matching.| +|`--prune`|Prune empty directories from output.| +|`--filelimit #`|Omit directories that contain more than # files.| +|`-o FILE`|Redirect STDOUT output to FILE.| +|`-i`|Do not output indentation.| diff --git a/docs/Linux-Commands/.recycle/097-the-printf-command.md b/docs/Linux-Commands/.recycle/097-the-printf-command.md new file mode 100755 index 0000000..9e80fa0 --- /dev/null +++ b/docs/Linux-Commands/.recycle/097-the-printf-command.md @@ -0,0 +1,184 @@ +# The `printf` command + +This command lets you print the value of a variable by formatting it using rules. It is pretty similar to the printf in C language. + +### Syntax: +``` +$printf [-v variable_name] format [arguments] +``` + +### Options: + +| OPTION | Description | +| --- | --- | +| `FORMAT` | FORMAT controls the output, and defines the way that the ARGUMENTs will be expressed in the output | +| `ARGUMENT` | An ARGUMENT will be inserted into the formatted output according to the definition of FORMAT | +| `--help` | Display help and exit | | +| `--version` | Output version information adn exit | | + +### Formats: + +The anatomy of the FORMAT string can be extracted into three different parts, + +- _ordinary characters_, which are copied exactly the same characters as were used originally to the output. +- _interpreted character_ sequences, which are escaped with a backslash ("\\"). +- _conversion specifications_, this one will define the way the ARGUMENTs will be expressed as part of the output. + + +You can see those parts in this example, + +``` +printf " %s is where over %d million developers shape \"the future of sofware.\" " Github 65 +``` + +The output: + +``` +Github is where over 65 million developers shape "the future of sofware." +``` + +There are two conversion specifications `%s` and `%d`, and there are two escaped characters which are the opening and closing double-quotes wrapping the words of _the future of software_. Other than that are the ordinary characters. + +### Conversion Specifications: + +Each conversion specification begins with a `%` and ends with a `conversion character`. Between the `%` and the `conversion character` there may be, in order: + +| | | +| --- | --- | +| `-` | A minus sign. This tells printf to left-adjust the conversion of the argument | +| _number_ | An integer that specifies field width; printf prints a conversion of ARGUMENT in a field at least number characters wide. If necessary it will be padded on the left (or right, if left-adjustment is called for) to make up the field width | +| `.` | A period, which separates the field width from the precision | +| _number_ | An integer, the precision, which specifies the maximum number of characters to be printed from a string, or the number of digits after the decimal point of a floating-point value, or the minimum number of digits for an integer | +| `h` or `l` | These differentiate between a short and a long integer, respectively, and are generally only needed for computer programming | + +The conversion characters tell `printf` what kind of argument to print out, are as follows: + +| Conversion char | Argument type | +| --- | --- | +| `s` | A string | +| `c` | An integer, expressed as a character corresponds ASCII code | +| `d, i` | An integer as a decimal number | +| `o` | An integer as an unsigned octal number | +| `x, X` | An integer as an unsigned hexadecimal number | +| `u` | An integer as an unsigned decimal number | +| `f` | A floating-point number with a default precision of 6 | +| `e, E` | A floating-point number in scientific notation | +| `p` | A memory address pointer | +| `%` | No conversion | + + + +Here is the list of some examples of the `printf` output the ARGUMENT. we can put any word but in this one we put a 'linuxcommand` word and enclosed it with quotes so we can see easier the position related to the whitespaces. + +| FORMAT string | ARGUMENT string | Output string | +| --- | --- | --- | +| `"%s"` | `"linuxcommand"` | "linuxcommand" | +| `"%5s"` | `"linuxcommand"` | "linuxcommand" | +| `"%.5s"` | `"linuxcommand"` | "linux" | +| `"%-8s"` | `"linuxcommand"` | "linuxcommand" | +| `"%-15s"` | `"linuxcommand"` | "linuxcommand " | +| `"%12.5s"` | `"linuxcommand"` | " linux" | +| `"%-12.5"` | `"linuxcommand"` | "linux " | +| `"%-12.4"` | `"linuxcommand"` | "linu " | + +Notes: + +- `printf` requires the number of conversion strings to match the number of ARGUMENTs +- `printf` maps the conversion strings one-to-one, and expects to find exactly one ARGUMENT for each conversion string +- Conversion strings are always interpreted from left to right. + +Here's the example: + +The input + +``` +printf "We know %f is %s %d" 12.07 "larger than" 12 +``` + +The output: + +``` +We know 12.070000 is larger than 12 +``` + +The example above shows 3 arguments, _12.07_, _larger than_, and _12_. Each of them interpreted from left to right one-to-one with the given 3 conversion strings (`%f`, `%d`, `%s`). + +Character sequences which are interpreted as special characters by `printf`: + +| Escaped char | Description | +| --- | --- | +| `\a` | issues an alert (plays a bell). Usually ASCII BEL characters | +| `\b` | prints a backspace | +| `\c` | instructs `printf` to produce no further output | +| `\e` | prints an escape character (ASCII code 27) | +| `\f` | prints a form feed | +| `\n` | prints a newline | +| `\r` | prints a carriage return | +| `\t` | prints a horizontal tab | +| `\v` | prints a vertical tab | +| `\"` | prints a double-quote (") | +| `\\` | prints a backslash (\) | +| `\NNN` | prints a byte with octal value `NNN` (1 to 3 digits) +| `\xHH` | prints a byte with hexadecimal value `HH` (1 to 2 digits) +| `\uHHHH`| prints the unicode character with hexadecimal value `HHHH` (4 digits) | +| `\UHHHHHHHH` | prints the unicode character with hexadecimal value `HHHHHHHH` (8 digits) | +| `%b` | prints ARGUMENT as a string with "\\" escapes interpreted as listed above, with the exception that octal escapes take the form `\0` or `\0NN` | + + +### Examples: +The format specifiers usually used with printf are stated in the examples below: + +- %s + +``` +$printf "%s\n" "Printf command documentation!" +``` +This will print `Printf command documentation!` in the shell. + +### Other important attributes of printf command: + +- `%b` - Prints arguments by expanding backslash escape sequences. +- `%q` - Prints arguments in a shell-quoted format which is reusable as input. +- `%d` , `%i` - Prints arguments in the format of signed decimal integers. +- `%u` - Prints arguments in the format of unsigned decimal integers. +- `%o` - Prints arguments in the format of unsigned octal(base 8) integers. +- `%x`, `%X` - Prints arguments in the format of unsigned hexadecimal(base 16) integers. %x prints lower-case letters and %X prints upper-case letters. +- `%e`, `%E` - Prints arguments in the format of floating-point numbers in exponential notation. %e prints lower-case letters and %E prints upper-case. +- `%a`, `%A` - Prints arguments in the format of floating-point numbers in hexadecimal(base 16) fractional notation. %a prints lower-case letters and %A prints upper-case. +- `%g`, `%G` - Prints arguments in the format of floating-point numbers in normal or exponential notation, whichever is more appropriate for the given value and precision. %g prints lower-case letters and %G prints upper-case. +- `%c` - Prints arguments as single characters. +- `%f` - Prints arguments as floating-point numbers. +- `%s` - Prints arguments as strings. +- `%%` - Prints a "%" symbol. + + +#### More Examples: + +The input: +``` +printf 'Hello\nyoung\nman!' +``` +The output: + +``` +hello +young +man! +``` + +The two `\n` break the sentence into 3 parts of words. + + + +The input: +``` +printf "%f\n" 2.5 5.75 +``` + +The output +``` +2.500000 +5.750000 +``` + +The `%f` specifier combined with the `\n` interpreted the two arguments in the form of floating point in the seperated new lines. \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/098-the-cut-command.md b/docs/Linux-Commands/.recycle/098-the-cut-command.md new file mode 100755 index 0000000..0937705 --- /dev/null +++ b/docs/Linux-Commands/.recycle/098-the-cut-command.md @@ -0,0 +1,42 @@ +# The `cut` command + +The `cut` command lets you remove sections from each line of files. Print selected parts of lines from each FILE to standard output. With no FILE, or when FILE is -, read standard input. + +### Usage and Examples: + +1. Selecting specific fields in a file +``` +cut -d "delimiter" -f (field number) file.txt +``` + +2. Selecting specific characters: +``` +cut -c [(k)-(n)/(k),(n)/(n)] filename +``` +Here, **k** denotes the starting position of the character and **n** denotes the ending position of the character in each line, if _k_ and _n_ are separated by “-” otherwise they are only the position of character in each line from the file taken as an input. + +3. Selecting specific bytes: +``` +cut -b 1,2,3 filename //select bytes 1,2 and 3 +cut -b 1-4 filename //select bytes 1 through 4 +cut -b 1- filename //select bytes 1 through the end of file +cut -b -4 filename //select bytes from the beginning till the 4th byte +``` +**Tabs and backspaces** are treated like as a character of 1 byte. + +### Syntax: + +``` +cut OPTION... [FILE]... +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-b`|`--bytes=LIST`|select only these bytes| +|`-c`|`--characters=LIST`|select only these characters| +|`-d`|`--delimiter=DELIM`|use DELIM instead of TAB for field delimiter| +|`-f`|`--fields`|select only these fields; also print any line that contains no delimiter character, unless the -s option is specified| +|`-s`|`--only-delimited`|do not print lines not containing delimiters| +|`-z`|`--zero-terminated`|line delimiter is NUL, not newline| diff --git a/docs/Linux-Commands/.recycle/099-the-sed-command.md b/docs/Linux-Commands/.recycle/099-the-sed-command.md new file mode 100755 index 0000000..3726a1e --- /dev/null +++ b/docs/Linux-Commands/.recycle/099-the-sed-command.md @@ -0,0 +1,53 @@ +# The `sed` command + +`sed` command stands for stream editor. A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipeline). For instance, it can perform lot’s of functions on files like searching, find and replace, insertion or deletion. While in some ways it is similar to an editor which permits scripted edits (such as `ed`), `sed` works by making only one pass over the input(s), and is consequently more efficient. But it is sed's ability to filter text in a pipeline that particularly distinguishes it from other types of editors. + +The most common use of `sed` command is for a substitution or for find and replace. By using sed you can edit files even without opening it, which is a much quicker way to find and replace something in the file. It supports basic and extended regular expressions that allow you to match complex patterns. Most Linux distributions come with GNU and `sed` is pre-installed by default. + +### Examples: + +1. To Find and Replace String with `sed` +``` +sed -i 's/{search_regex}/{replace_value}/g' input-file +``` + +2. For Recursive Find and Replace *(along with `find`)* + +> Sometimes you may want to recursively search directories for files containing a string and replace the string in all files. This can be done using commands such as find to recursively find files in the directory and piping the file names to `sed`. +The following command will recursively search for files in the current working directory and pass the file names to `sed`. It will recursively search for files in the current working directory and pass the file names to `sed`. + +``` +find . -type f -exec sed -i 's/{search_regex}/{replace_value}/g' {} + +``` + +### Syntax: + +``` +sed [OPTION]... {script-only-if-no-other-script} [INPUT-FILE]... +``` + +- `OPTION` - sed options in-place, silent, follow-symlinks, line-length, null-data ...etc. +- `{script-only-if-no-other-script}` - Add the script to command if available. +- `INPUT-FILE` - Input Stream, A file or input from a pipeline. + +If no option is given, then the first non-option argument is taken as the sed script to interpret. All remaining arguments are names of input files; if no input files are specified, then the standard input is read. + +GNU sed home page: [http://www.gnu.org/software/sed/](http://www.gnu.org/software/sed/) + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-i[SUFFIX]`|
--in-place[=SUFFIX]
|Edit files in place (makes backup if SUFFIX supplied).| +|`-n`|
--quiet, --silent
|Suppress automatic printing of pattern space.| +|`-e script`|
--expression=script
|Add the script to the commands to be executed.| +|`-f script-file`|
--file=script-file
|Add the contents of script-file to the commands to be executed.| +|`-l N`|
--line-length=N
|Specify the desired line-wrap length for the `l` command.| +|`-r`|
--regexp-extended
|Use extended regular expressions in the script.| +|`-s`|
--separate
|Consider files as separate rather than as a single continuous long stream.| +|`-u`|
--unbuffered
|Load minimal amounts of data from the input files and flush the output buffers more often.| +|`-z`|
--null-data
|Separate lines by NULL characters.| + +### Before you begin + +It may seem complicated and complex at first, but searching and replacing text in files with sed is very simple. + +To find out more: [https://www.gnu.org/software/sed/manual/sed.html](https://www.gnu.org/software/sed/manual/sed.html) \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/103-the-rmdir-command.md b/docs/Linux-Commands/.recycle/103-the-rmdir-command.md new file mode 100755 index 0000000..cf31ec6 --- /dev/null +++ b/docs/Linux-Commands/.recycle/103-the-rmdir-command.md @@ -0,0 +1,29 @@ +# The `rmdir` command + +The **rmdir** command is used to remove empty directories from the filesystem in Linux. The rmdir command removes each and every directory specified in the command line only if these directories are empty. + +### Usage and Examples: + +1. remove directory and its ancestors +``` +rmdir -p a/b/c // is similar to 'rmdir a/b/c a/b a' +``` +2. remove multiple directories +``` +rmdir a b c // removes empty directories a,b and c +``` + +### Syntax: + +``` +rmdir [OPTION]... DIRECTORY... +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-`|`--ignore-fail-on-non-empty`|ignore each failure that is solely because a directory is non-empty| +|`-p`|`--parents`|remove DIRECTORY and its ancestors| +|`-d`|`--delimiter=DELIM`|use DELIM instead of TAB for field delimiter| +|`-v`|`--verbose`|output a diagnostic for every directory processed| diff --git a/docs/Linux-Commands/.recycle/108-the-screen-command.md b/docs/Linux-Commands/.recycle/108-the-screen-command.md new file mode 100755 index 0000000..947df3e --- /dev/null +++ b/docs/Linux-Commands/.recycle/108-the-screen-command.md @@ -0,0 +1,45 @@ +# The `screen` command + +`screen` - With screen you can start a screen session and then open any number of windows (virtual terminals) inside that session. +Processes running in Screen will continue to run when their window is not visible even if you get disconnected. This is very +handy for running long during session such as bash scripts that run very long. + +To start a screen session you type `screen`, this will open a new screen session with a virtual terminal open. + +Below are some most common commands for managing Linux Screen Windows: + +|**Command** |**Description** | +|:---|:---| +|`Ctrl+a`+ `c`|Create a new window (with shell).| +|`Ctrl+a`+ `"`|List all windows. +|`Ctrl+a`+ `0`|Switch to window 0 (by number). +|`Ctrl+a`+ `A`|Rename the current window. +|`Ctrl+a`+ `S`|Split current region horizontally into two regions. +|`Ctrl+a`+ `'`|Split current region vertically into two regions. +|`Ctrl+a`+ `tab`|Switch the input focus to the next region. +|`Ctrl+a`+ `Ctrl+a`|Toggle between the current and previous windows +|`Ctrl+a`+ `Q`|Close all regions but the current one. +|`Ctrl+a`+ `X`|Close the current region. + + +## Restore a Linux Screen + +To restore to a screen session you type `screen -r`, if you have more than one open screen session you have to add the +session id to the command to connect to the right session. + +## Listing all open screen sessions + +To find the session ID you can list the current running screen sessions with: + +`screen -ls` + +There are screens on: +``` +18787.pts-0.your-server (Detached) +15454.pts-0.your-server (Detached) +2 Sockets in /run/screens/S-yourserver. +``` + +If you want to restore screen 18787.pts-0, then type the following command: + +`screen -r 18787` diff --git a/docs/Linux-Commands/.recycle/109-the-nc-command.md b/docs/Linux-Commands/.recycle/109-the-nc-command.md new file mode 100755 index 0000000..52f8ad0 --- /dev/null +++ b/docs/Linux-Commands/.recycle/109-the-nc-command.md @@ -0,0 +1,86 @@ +# The `nc` command + +The `nc` (or netcat) command is used to perform any operation involving TCP (Transmission Control Protocol, connection oriented), UDP (User Datagram Protocol, connection-less, no guarantee of data delivery) or UNIX-domain sockets. It can be thought of as swiss-army knife for communication protocol utilities. + +### Syntax: + +``` +nc [options] [ip] [port] +``` + +### Examples: + +#### 1. Open a TCP connection to port 80 of host, using port 1337 as source port with timeout of 5s: + +```bash +$ nc -p 1337 -w 5 host.ip 80 +``` + +#### 2. Open a UDP connection to port 80 on host: + +```bash +$ nc -u host.ip 80 +``` + +#### 3. Create and listen on UNIX-domain stream socket: + +```bash +$ nc -lU /var/tmp/dsocket +``` + +#### 4. Create a basic server/client model: + +This creates a connection, with no specific server/client sides with respect to nc, once the connection is established. + +```bash +$ nc -l 1234 # in one console + +$ nc 127.0.0.1 1234 # in another console +``` + +#### 5. Build a basic data transfer model: + +After the file has been transferred, sequentially, the connection closes automatically + +```bash +$ nc -l 1234 > filename.out # to start listening in one console and collect data + +$ nc host.ip 1234 < filename.in +``` + +#### 6. Talk to servers: + +Basic example of retrieving the homepage of the host, along with headers. + +```bash +$ printf "GET / HTTP/1.0\r\n\r\n" | nc host.ip 80 +``` + +#### 7. Port scanning: + +Checking which ports are open and running services on target machines. `-z` flag commands to inform about those rather than initiate a connection. + +```bash +$ nc -zv host.ip 20-2000 # range of ports to check for +``` + +### Flags and their Functionalities: + +| **Short Flag** | **Description** | +| -------------- | ----------------------------------------------------------------- | +| `-4` | Forces nc to use IPv4 addresses | +| `-6` | Forces nc to use IPv6 addresses | +| `-b` | Allow broadcast | +| `-D` | Enable debugging on the socket | +| `-i` | Specify time interval delay between lines sent and received | +| `-k` | Stay listening for another connection after current is over | +| `-l` | Listen for incoming connection instead of initiate one to remote | +| `-T` | Specify length of TCP | +| `-p` | Specify source port to be used | +| `-r` | Specify source and/or destination ports randomly | +| `-s` | Specify IP of interface which is used to send the packets | +| `-U` | Use UNIX-domain sockets | +| `-u` | Use UDP instead of TCP as protocol | +| `-w` | Declare a timeout threshold for idle or unestablished connections | +| `-x` | Should use specified protocol when talking to proxy server | +| `-z` | Specify to scan for listening daemons, without sending any data | diff --git a/docs/Linux-Commands/.recycle/110-the-make-command.md b/docs/Linux-Commands/.recycle/110-the-make-command.md new file mode 100755 index 0000000..29b5caf --- /dev/null +++ b/docs/Linux-Commands/.recycle/110-the-make-command.md @@ -0,0 +1,48 @@ +# The `make` command + +The `make` command is used to automate the reuse of multiple commands in certain directory structure. + +An example for that would be the use of `terraform init`, `terraform plan`, and `terraform validate` while having to change different subscriptions in Azure. This is usually done in the following steps: + +``` +az account set --subscription "Subscription - Name" +terraform init +``` + +How the `make` command can help us is it can automate all of that in just one go: +```make tf-init``` + +### Syntax: + +``` +make [ -f makefile ] [ options ] ... [ targets ] ... +``` + +### Example use (guide): + +#### 1. Create `Makefile` in your guide directory +#### 2. Include the following in your `Makefile` : +``` +hello-world: + echo "Hello, World!" + +hello-bobby: + echo "Hello, Bobby!" + +touch-letter: + echo "This is a text that is being inputted into our letter!" > letter.txt + +clean-letter: + rm letter.txt +``` +#### 3. Execute ```make hello-world``` - this echoes "Hello, World" in our terminal. +#### 4. Execute ```make hello-bobby``` - this echoes "Hello, Bobby!" in our terminal. +#### 5. Execute ```make touch-letter``` - This creates a text file named `letter.txt` and populates a line in it. +#### 6. Execute ```make clean-letter``` + + + +### References to lenghtier and more contentful tutorials: + +(linoxide - linux make command examples)[https://linoxide.com/linux-make-command-examples/] +(makefiletutorial.com - the name itself gives it out)[https://makefiletutorial.com/] \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/111-the-basename-command.md b/docs/Linux-Commands/.recycle/111-the-basename-command.md new file mode 100755 index 0000000..deffb3f --- /dev/null +++ b/docs/Linux-Commands/.recycle/111-the-basename-command.md @@ -0,0 +1,90 @@ + +# The `basename` command + +The `basename` is a command-line utility that strips directory from given file names. Optionally, it can also remove any trailing suffix. It is a simple command that accepts only a few options. + +### Examples + +The most basic example is to print the file name with the leading directories removed: + +```bash +basename /etc/bar/foo.txt +``` + +The output will include the file name: + +```bash +foo.txt +``` + +If you run basename on a path string that points to a directory, you will get the last segment of the path. In this example, /etc/bar is a directory. + +```bash +basename /etc/bar +``` + +Output + +```bash +bar +``` + +The basename command removes any trailing `/` characters: + +```bash +basename /etc/bar/foo.txt/ +``` + +Output + +```bash +foo.txt +``` + +### Options + +1. By default, each output line ends in a newline character. To end the lines with NUL, use the -z (--zero) option. + +```bash +$ basename -z /etc/bar/foo.txt +foo.txt$ +``` + +2. The `basename` command can accept multiple names as arguments. To do so, invoke the command with the `-a` (`--multiple`) option, followed by the list of files separated by space. For example, to get the file names of `/etc/bar/foo.txt` and `/etc/spam/eggs.docx` you would run: + +```bash +basename -a /etc/bar/foo.txt /etc/spam/eggs.docx +``` + +```bash +foo.txt +eggs.docx +``` + +### Syntax + +The basename command supports two syntax formats: + +```bash +basename NAME [SUFFIX] +basename OPTION... NAME... +``` + +### Additional functionalities + +**Removing a Trailing Suffix**: To remove any trailing suffix from the file name, pass the suffix as a second argument: + +```bash +basename /etc/hostname name +host +``` + +Generally, this feature is used to strip file extensions + +### Help Command + +Run the following command to view the complete guide to `basename` command. + +```bash +man basename +``` diff --git a/docs/Linux-Commands/.recycle/112-the-banner-command.md b/docs/Linux-Commands/.recycle/112-the-banner-command.md new file mode 100755 index 0000000..f47ee69 --- /dev/null +++ b/docs/Linux-Commands/.recycle/112-the-banner-command.md @@ -0,0 +1,33 @@ +# The `banner` command + +The `banner` command writes ASCII character Strings to standard output in large letters. Each line in the output can be up to 10 uppercase or lowercase characters in length. On output, all characters appear in uppercase, with the lowercase input characters appearing smaller than the uppercase input characters. + +Note: If you will define more than one NUMBER with sleep command then this command will delay for the sum of the values. + +### Examples : + +1. To display a banner at the workstation, enter: + +``` +banner LINUX! +``` + + +2. To display more than one word on a line, enclose the text in quotation marks, as follows: + +``` +banner "Intro to" Linux +``` + +> This displays Intro to on one line and Linux on the next + + +3. Printing “101LinuxCommands” in large letters. + +``` +banner 101LinuxCommands +``` + +> It will print only 101LinuxCo as banner has a default capacity of 10 + +--- diff --git a/docs/Linux-Commands/.recycle/114-the-which-command.md b/docs/Linux-Commands/.recycle/114-the-which-command.md new file mode 100755 index 0000000..509787b --- /dev/null +++ b/docs/Linux-Commands/.recycle/114-the-which-command.md @@ -0,0 +1,64 @@ +# The `which` command + +`which` command identifies the executable binary that launches when you issue a command to the shell. +If you have different versions of the same program on your computer, you can use which to find out which one the shell will use. + +It has 3 return status as follows: + + 0 : If all specified commands are found and executable. + 1 : If one or more specified commands is nonexistent or not executable. + 2 : If an invalid option is specified. + +### Examples + +1. To find the full path of the ls command, type the following: + +``` +which ls +``` + +2. We can provide more than one arguments to the which command: + +``` +which netcat uptime ping +``` + + The which command searches from left to right, and if more than one matches are found in the directories listed in the PATH path variable, which will print only the first one. + +3. To display all the paths for the specified command: + +``` +which [filename] -a +``` + +4. To display the path of node executable files, execute the command: + +``` +which node +``` + +5. To display the path of Java executable files, execute: + +``` +which java +``` + +### Syntax + +``` +which [filename1] [filename2] ... +``` + +You can pass multiple programs and commands to which, and it will check them in order. + +For example: + +```which ping cat uptime date head``` + +### Options + +-a : List all instances of executables found (instead of just the first +one of each). + +-s : No output, just return 0 if all the executables are found, or 1 +if some were not found \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/117-the-nice-command.md b/docs/Linux-Commands/.recycle/117-the-nice-command.md new file mode 100755 index 0000000..ceb787b --- /dev/null +++ b/docs/Linux-Commands/.recycle/117-the-nice-command.md @@ -0,0 +1,35 @@ + +# The `nice/renice` command + +The `nice/renice` commands is used to modify the priority of the program to be executed. +The priority range is between -20 and 19 where 19 is the lowest priority. +### Examples: + +1. Running cc command in the background with a lower priority than default (slower): + +``` +nice -n 15 cc -c *.c & +``` + +2. Increase the priority to all processes belonging to group "test": + +``` +renice --20 -g test +``` + +### Syntax: + +``` +nice [ -Increment| -n Increment ] Command [ Argument ... ] +``` + + +### Flags : + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-Increment`|
-
|Increment is the value of priority you want to assign.| +|`-n Increment`|
-
|Same as `-Increment` + + + diff --git a/docs/Linux-Commands/.recycle/118-the-wc-command.md b/docs/Linux-Commands/.recycle/118-the-wc-command.md new file mode 100755 index 0000000..a6e71d5 --- /dev/null +++ b/docs/Linux-Commands/.recycle/118-the-wc-command.md @@ -0,0 +1,42 @@ +# The `wc` command + +the `wc` command stands for word count. It's used to count the number of lines, words, and bytes *(characters)* in a file or standard input then prints the result to the standard output. + + +### Examples: + +1. To count the number of lines, words and characters in a file in order: + +``` +wc file.txt +``` + +2. To count the number of directories in a directory: + +``` +ls -F | grep / | wc -l +``` + +### Syntax: + +```bash +wc [OPTION]... [FILE]... +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-c` | `--bytes` | print the byte counts| +|`-m` | `--chars` | print the character counts| +|`-l` | `--lines` | print the newline counts| +|
-
| `--files0-from=F` | read input from the files specified by NUL-terminated names in file F. If F is `-` then read names from standard input| +|`-L` | `--max-line-length` | print the maximum display width| +|`-w` | `--words` | print the word counts| + + + +### Additional Notes: + +* Passing more than one file to `wc` command prints the counts for each file and the total conuts of them. +* you can combine more whan one flag to print the result as you want. diff --git a/docs/Linux-Commands/.recycle/119-the-tr-command.md b/docs/Linux-Commands/.recycle/119-the-tr-command.md new file mode 100755 index 0000000..b3ca605 --- /dev/null +++ b/docs/Linux-Commands/.recycle/119-the-tr-command.md @@ -0,0 +1,65 @@ +# The `tr` command + +The tr command in UNIX is a command line utility for translating or deleting characters. +It supports a range of transformations including uppercase to lowercase, squeezing repeating characters, deleting specific characters and basic find and replace. +It can be used with UNIX pipes to support more complex translation. tr stands for translate. + +### Examples: + +1. Convert all lowercase letters in file1 to uppercase. + +``` +$ cat file1 +foo +bar +baz +tr a-z A-Z < file1 +FOO +BAR +BAZ +``` + +2. Make consecutive line breaks into one. + +``` +$ cat file1 +foo + + +bar + + +baz +$ tr -s "\n" < file1 +foo +bar +baz +``` + +3. Remove the newline code. + +``` +$ cat file1 +foo +bar +baz +$ tr -d "\n" < file1 +foobarbaz% +``` + +### Syntax: + +The general syntax for the tr command is as follows: + +``` +tr [options] string1 [string2] +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :------------- | :------------ | :------------------------------------------------------------------------------------------------------------ | +| `-C` | | Complement the set of characters in string1, that is `-C ab` includes every character except for `a` and `b`. | +| `-c` | | Same as -C. | +| `-d` | | Delete characters in string1 from the input. | +| `-s` | | If there is a sequence of characters in string1, combine them into one. | diff --git a/docs/Linux-Commands/.recycle/121-the-wait-command.md b/docs/Linux-Commands/.recycle/121-the-wait-command.md new file mode 100755 index 0000000..fecb9df --- /dev/null +++ b/docs/Linux-Commands/.recycle/121-the-wait-command.md @@ -0,0 +1,27 @@ +# The `Wait` commands + +It is a command that waits for completing any running process of given id. if the process id is not given then it waits for all current child processes to complete. + +## Example + +This example shows how the `wait` command works :
+ +**Step-1**: + +Create a file named "wait_example.sh" and add the following script to it. + +``` +#!/bin/bash +echo "Wait command" & +process_id=$! +wait $process_id +echo "Exited with status $?" +``` + +**Step-2**: + +Run the file with bash command. + +``` +$ bash wait_example.sh +``` diff --git a/docs/Linux-Commands/.recycle/122-the-zcat-command.md b/docs/Linux-Commands/.recycle/122-the-zcat-command.md new file mode 100755 index 0000000..4cc3269 --- /dev/null +++ b/docs/Linux-Commands/.recycle/122-the-zcat-command.md @@ -0,0 +1,30 @@ +# The `zcat` command + +The `zcat` allows you to look at a compressed file. + + +### Examples: + +1. To view the content of a compressed file: + +``` +~$ zcat test.txt.gz +Hello World +``` + +2. It can also Works with multiple files: + +``` +~$ zcat test2.txt.gz test.txt.gz +hello +Hello world +``` + +### Syntax: + +The general syntax for the `zcat` command is as follows: + +``` +zcat [ -n ] [ -V ] [ File ... ] +``` + diff --git a/docs/Linux-Commands/.recycle/123-the-fold-command.md b/docs/Linux-Commands/.recycle/123-the-fold-command.md new file mode 100755 index 0000000..8e76a8e --- /dev/null +++ b/docs/Linux-Commands/.recycle/123-the-fold-command.md @@ -0,0 +1,55 @@ +# The `fold` command + +The `fold` command in Linux wraps each line in an input file to fit a specified width and prints it to the standard output. + +By default, it wraps lines at a maximum width of 80 columns but this is configurable. + +To fold input using the fold command pass a file or standard input to the command. + + +### Syntax: + +``` +fold [OPTION]... [FILE]... +``` + +### Options + +**-w** : By using this option in fold command, we can limit the width by number of columns. + +By using this command we change the column width from default width of 80. +Syntax: + +``` +fold -w[n] [FILE] +``` + Example: wrap the lines of file1.txt to a width of 60 columns + +``` +fold -w60 file1.txt +``` + + +**-b** : This option of fold command is used to limit the width of the output by the number of bytes rather than the number of columns. + +By using this we can enforce the width of the output to the number of bytes. + +``` +fold -b[n] [FILE] +``` + +Example: limit the output width of the file to 40 bytes and the command breaks the output at 40 bytes. + +``` +fold -b40 file1.txt +``` + +**-s** : This option is used to break the lines on spaces so that words are not broken. + +If a segment of the line contains a blank character within the first width column positions, break the line after the last such blank character meeting the width constraints. + +``` +fold -w[n] -s [FILE] +``` + + diff --git a/docs/Linux-Commands/.recycle/124-the-quota-command.md b/docs/Linux-Commands/.recycle/124-the-quota-command.md new file mode 100755 index 0000000..a7ce051 --- /dev/null +++ b/docs/Linux-Commands/.recycle/124-the-quota-command.md @@ -0,0 +1,28 @@ +# The `quota` command + +The `quota` display disk usage and limits. + + +### Installation: + +You can simply go ahead and install quota on ubuntu systems by running: + +``` +sudo apt-get install quota +``` + +for Debian use the install command without sudo: + +``` +apt-get install quota +``` + + +### Syntax: + +The general syntax for the `quota` command is as follows: + +``` +quota [ -u [ User ] ] [ -g [ Group ] ] [ -v | -q ] +``` + diff --git a/docs/Linux-Commands/.recycle/125-the-aplay-command.md b/docs/Linux-Commands/.recycle/125-the-aplay-command.md new file mode 100755 index 0000000..4dca208 --- /dev/null +++ b/docs/Linux-Commands/.recycle/125-the-aplay-command.md @@ -0,0 +1,55 @@ +# The `aplay` command + +`aplay` is a command-line audio player for ALSA(Advanced Linux Sound Architecture) sound card drivers. It supports several file formats and multiple soundcards with multiple devices. It is basically used to play audio on command-line interface. aplay is much the same as arecord only it plays instead of recording. For supported soundfile formats, the sampling rate, bit depth, and so forth can be automatically determined from the soundfile header. + +## Syntax: + +``` +$ aplay [flags] [filename [filename]] ... +``` + +## Options: + +``` +-h, –help : Show the help information. +-d, –duration=# : Interrupt after # seconds. +-r, –rate=# : Sampling rate in Hertz. The default rate is 8000 Hertz. +–version : Print current version. +-l, –list-devices : List all soundcards and digital audio devices. +-L, –list-pcms : List all PCMs(Pulse Code Modulation) defined. +-D, –device=NAME : Select PCM by name. +``` + +Note: This command contain various other options that we normally don’t need. If you want to know more about you can simply run following command on your terminal. + +``` +aplay --help +``` + +## Examples : + +1. To play audio for only 10 secs at 2500hz frequency. + + ``` + $ aplay -d 10 -r 2500hz sample.mp3 + ``` + + > Plays sample.mp3 file for only 10 secs at 2500hz frequency. + +2. To play full audio clip at 2500hz frezuency. + + ``` + $ aplay -r 2500hz sample.mp3 + ``` + + > Plays sample.mp3 file at 2500hz frezuency. + +3. To Display version information. + + ``` + $ aplay --version + ``` + + > Displays version information. For me it shows aplay: vesrion 1.1.0 + +--- diff --git a/docs/Linux-Commands/.recycle/126-the-spd-say-command.md b/docs/Linux-Commands/.recycle/126-the-spd-say-command.md new file mode 100755 index 0000000..849bfb2 --- /dev/null +++ b/docs/Linux-Commands/.recycle/126-the-spd-say-command.md @@ -0,0 +1,82 @@ +# The `spd-say` command + +`spd-say` sends text-to-speech output request to speech-dispatcher process which handles it + and ideally outputs the result to the audio system. + +## Syntax: + +``` +$ spd-say [options] "some text" +``` + +## Options: + +``` +-r, --rate + Set the rate of the speech (between -100 and +100, default: 0) + +-p, --pitch + Set the pitch of the speech (between -100 and +100, default: 0) + +-i, --volume + Set the volume (intensity) of the speech (between -100 and +100, default: 0) + +-o, --output-module + Set the output module + +-l, --language + Set the language (iso code) + +-t, --voice-type + Set the preferred voice type (male1, male2, male3, female1, female2, female3, + child_male, child_female) + +-m, --punctuation-mode + Set the punctuation mode (none, some, all) + +-s, --spelling + Spell the message + +-x, --ssml + Set SSML mode on (default: off) + +-e, --pipe-mode + Pipe from stdin to stdout plus Speech Dispatcher + +-P, --priority + Set priority of the message (important, message, text, notification, progress; + default: text) + +-N, --application-name + Set the application name used to establish the connection to specified string value + (default: spd-say) + +-n, --connection-name + Set the connection name used to establish the connection to specified string value + (default: main) + +-w, --wait + Wait till the message is spoken or discarded + +-S, --stop + Stop speaking the message being spoken in Speech Dispatcher + +-C, --cancel + Cancel all messages in Speech Dispatcher + +-v, --version + Print version and copyright info + +-h, --help + Print this info +``` + +## Examples : + +1. To Play the given text as the sound. + +``` +$ spd-say "Hello" +``` + +>Plays "Hello" in sound. diff --git a/docs/Linux-Commands/.recycle/127-the-xeyes-command.md b/docs/Linux-Commands/.recycle/127-the-xeyes-command.md new file mode 100755 index 0000000..db9c3ae --- /dev/null +++ b/docs/Linux-Commands/.recycle/127-the-xeyes-command.md @@ -0,0 +1,15 @@ +# The `xeyes` command + +Xeyes is a graphical user interface program that creates a set of eyes on the desktop that follow the movement of the mouse cursor. It seems much of a funny command, than of any useful use. Being funny is as much useful, is another aspect. + +### Syntax: + +``` +xeyes +``` + +### What is the purpose of xeyes? + +`xeyes` is not for fun, at least not only. The purpose of this program is to let you follow the mouse pointer which is sometimes hard to see. It is very useful on multi-headed computers, where monitors are separated by some distance, and if someone (say teacher at school) wants to present something on the screen, the others on their monitors can easily follow the mouse with `xeyes`. + + diff --git a/docs/Linux-Commands/.recycle/129-the-nl-command.md b/docs/Linux-Commands/.recycle/129-the-nl-command.md new file mode 100755 index 0000000..3931185 --- /dev/null +++ b/docs/Linux-Commands/.recycle/129-the-nl-command.md @@ -0,0 +1,32 @@ +# The `nl` command + +The “nl” command enumerates lines in a file. A different way of viewing the contents of a file, the “nl” command can be very useful for many tasks. +## Syntax +``` +nl [ -b Type ] [ -f Type ] [ -h Type ] [ -l Number ] [ -d Delimiter ] [ -i Number ] [ -n Format ] [ -v Number ] [ -w Number ] [ -p ] [ -s Separator ] [ File ] +``` +## Examples: +1. To number all lines: +``` +nl -ba chap1 +``` + +2. Displays all the text lines: +``` +[server@ssh ~]$ nl states +1 Alabama +2 Alaska +3 Arizona +4 Arkansas +5 California +6 Colorado +7 Connecticut. +8 Delaware +``` + +3. Specify a different line number format +``` +nl -i10 -nrz -s:: -v10 -w4 chap1 +``` + +You can name only one file on the command line. You can list the flags and the file name in any order. diff --git a/docs/Linux-Commands/.recycle/130-the-pidof-command.md b/docs/Linux-Commands/.recycle/130-the-pidof-command.md new file mode 100755 index 0000000..a46d07b --- /dev/null +++ b/docs/Linux-Commands/.recycle/130-the-pidof-command.md @@ -0,0 +1,68 @@ +# The `pidof` command + +The `pidof` is a command-line utility that allows you to find the process ID of a running program. + +## Syntax +``` +pidof [OPTIONS] PROGRAM_NAME +``` + +To view the help message and all options of the command: +``` +[user@home ~]$ pidof -h + + -c Return PIDs with the same root directory + -d Use the provided character as output separator + -h Display this help text + -n Avoid using stat system function on network shares + -o Omit results with a given PID + -q Quiet mode. Do not display output + -s Only return one PID + -x Return PIDs of shells running scripts with a matching name + -z List zombie and I/O waiting processes. May cause pidof to hang. +``` + +## Examples: +To find the PID of the SSH server, you would run: + +``` +pidof sshd +``` + +If there are running processes with names matching `sshd`, their PIDs will be displayed on the screen. If no matches are found, the output will be empty. + +``` +# Output +4382 4368 811 +``` + +`pidof` returns `0` when at least one running program matches with the requested name. Otherwise, the exit code is `1`. This can be useful when writing shell scripts. + +To be sure that only the PIDs of the program you are searching for are displayed, use the full pathname to the program as an argument. For example, if you have two running programs with the same name located in two different directories pidof will show PIDs of both running programs. + +By default, all PIDs of the matching running programs are displayed. Use the `-s` option to force pidof to display only one PID: + +``` +pidof -s program_name +``` + +The `-o` option allows you to exclude a process with a given PID from the command output: + +``` +pidof -o pid program_name +``` + +When pidof is invoked with the `-o` option, you can use a special PID named %PPID that represents the calling shell or shell script. + +To return only the PIDs of the processes that are running with the same root directory, use the `-c` option. +This option works only pidof is run as `root` or `sudo` user: + +``` +pidof -c pid program_name +``` + +## Conclusion + +The `pidof` command is used to find out the PIDs of a specific running program. + +`pidof` is a simple command that doesn’t have a lot of options. Typically you will invoke pidof only with the name of the program you are searching for. diff --git a/docs/Linux-Commands/.recycle/131-the-shuf-command.md b/docs/Linux-Commands/.recycle/131-the-shuf-command.md new file mode 100755 index 0000000..4f93364 --- /dev/null +++ b/docs/Linux-Commands/.recycle/131-the-shuf-command.md @@ -0,0 +1,172 @@ +# The `shuf` command + +The `shuf` command in Linux writes a random permutation of the input lines to standard output. It pseudo randomizes an input in the same way as the cards are shuffled. It is a part of GNU Coreutils and is not a part of POSIX. This command reads either from a file or standard input in bash and randomizes those input lines and displays the output. + +## Syntax +``` +# file shuf +shuf [OPTION] [FILE] + +# list shuf +shuf -e [OPTION]... [ARG] + +# range shuf +shuf -i LO-HI [OPTION] +``` + +Like other Linux commands, `shuf` command comes with `-–help` option: +``` +[user@home ~]$ shuf --help +Usage: shuf [OPTION]... [FILE] + or: shuf -e [OPTION]... [ARG]... + or: shuf -i LO-HI [OPTION]... +Write a random permutation of the input lines to standard output. + +With no FILE, or when FILE is -, read standard input. + +Mandatory arguments to long options are mandatory for short options too. + -e, --echo treat each ARG as an input line + -i, --input-range=LO-HI treat each number LO through HI as an input line + -n, --head-count=COUNT output at most COUNT lines + -o, --output=FILE write result to FILE instead of standard output + --random-source=FILE get random bytes from FILE + -r, --repeat output lines can be repeated + -z, --zero-terminated line delimiter is NUL, not newline +``` + +## Examples: + +### shuf command without any option or argument. + +``` +shuf +``` + +When `shuf` command is used without any argument in the command line, it takes input from the user until `CTRL-D` is entered to terminate the set of inputs. It displays the input lines in a shuffled form. If `1, 2, 3, 4 and 5` are entered as input lines, then it generates `1, 2, 3, 4 and 5` in random order in the output as seen in the illustration below: + +``` +[user@home ~]$ shuf +1 +2 +3 +4 +5 + +4 +5 +1 +2 +3 +``` + +Consider an example where Input is taken from the pipe: + +``` +{ +seq 5 | shuf +} +``` + +`seq 5` returns the integers sequentially from `1` to `5` while the `shuf` command takes it as input and shuffles the content i.e, the integers from `1` to `5`. Hence, `1` to `5` is displayed as output in random order. + +``` +[user@home ~]$ { +> seq 5 | shuf +> } +5 +4 +2 +3 +1 +``` + +### File shuf + +When `shuf` command is used without `-e` or `-i` option, then it operates as a file shuf i.e, it shuffles the contents of the file. The `` is the last parameter of the `shuf` command and if it is not given, then input has to be provided from the shell or pipe. + +Consider an example where input is taken from a file: + +``` +shuf file.txt +``` + +Suppose file.txt contains 6 lines, then the shuf command displays the input lines in random order as output. + +``` +[user@home ~]$ cat file.txt +line-1 +line-2 +line-3 +line-4 +line-5 + +[user@home ~]$ shuf file.txt +line-5 +line-4 +line-1 +line-3 +line-2 +``` + +Any number of lines can be randomized by using `-n` option. + +``` +shuf -n 2 file.txt +``` + +This will display any two random lines from the file. + +``` +line-5 +line-2 +``` + +### List shuf + +When `-e` option is used with shuf command, it works as a list shuf. The arguments of the command are taken as the input line for the shuf. + +Consider an example: + +``` +shuf -e A B C D E +``` + +It will take `A, B, C, D, E` as input lines, and will shuffle them to display the output. + +``` +A +C +B +D +E +``` + +Any number of input lines can be displayed using the `-n` option along with `-e` option. + +``` +shuf -e -n 2 A B C D E +``` + +This will display any two of the inputs. + +``` +E +A +``` + +### Range shuf + +When `-i` option is used along with `shuf` command, it acts as a `range shuf`. It requires a range of input as input where `L0` is the lower bound while `HI` is the upper bound. It displays integers from `L0-HI` in shuffled form. + +``` +[user@home ~]$ shuf -i 1-5 +4 +1 +3 +2 +5 +``` + +## Conclusion + +The `shuf` command helps you randomize input lines. And there are features to limit the number of output lines, repeat lines and even generate random positive integers. Once you're done practicing whatever we've discussed here, head to the tool's [man page](https://linux.die.net/man/1/shuf) to know more about it. \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/134-the-cmp-command.md b/docs/Linux-Commands/.recycle/134-the-cmp-command.md new file mode 100755 index 0000000..99f2d66 --- /dev/null +++ b/docs/Linux-Commands/.recycle/134-the-cmp-command.md @@ -0,0 +1,68 @@ +# The `cmp` command + +The `cmp` command is used to compare the two files byte by byte. + +Example: +``` +cmp file1.txt file2.txt +``` + +Syntax: +``` +cmp [option] File1 File2 +``` + +## Few Examples : + +1. ### Comparison of two files: + +Perform a simple comparison of the two files to check out if they differ from each other or not. + +Example: +``` +cmp File1 File2 +``` + +2. ### Comparing Files after Skipping a Specified Number of Bytes: + +Compare two files after skipping a certain number of bytes + +Example: +``` +cmp -i 2 list.txt list2.txt +``` + +Here “INT” represents the number of bytes to be skipped + +3. ### Display the Differing Bytes of the Files in the Output: + +Example: +``` +cmp -b list.txt list1.txt +``` +4. ### Display Byte Numbers and Differing Byte Values of the Files in the Output: + +Example: +``` +cmp -l list.txt list1.txt +``` + +5. ### Comparing the First “n” Number of Bytes of the Files: + +Example: +``` +cmp -n 10 list.txt list2.txt +``` +### Additional Flags and their Functionalities + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-b`|`--print-bytes`|print differing bytes| +|`-i`|`--ignore-initial=SKIP`|skip first SKIP bytes of both inputs| +|`-i`|`--ignore-initial=SKIP1:SKIP2`|skip first SKIP1 bytes of FILE1 and first SKIP2 bytes of FILE2| +|`-l`|`--verbose`|output byte numbers and differing byte values| +|`-n`|`--bytes=LIMIT`|compare at most LIMIT bytes| +|`-s`|`--quiet, --silent`|suppress all normal output| +|`v`|`--version`|output version information and exit| +||`--help`|Display this help and exit| + diff --git a/docs/Linux-Commands/.recycle/135-the-expr-command.md b/docs/Linux-Commands/.recycle/135-the-expr-command.md new file mode 100755 index 0000000..592e9a3 --- /dev/null +++ b/docs/Linux-Commands/.recycle/135-the-expr-command.md @@ -0,0 +1,48 @@ +# The `expr` command + +The `expr` command evaluates a given expression and displays its corresponding output. It is used for basic operations like addition, subtraction, multiplication, division, and modulus on integers and Evaluating regular expressions, string operations like substring, length of strings etc. + +## Syntax + +``` +expr expression +``` + +## Few Examples: +1. ### Perform basic arithmetic operations using expr command +``` +expr 7 + 14 +expr 7 * 8 +``` + +2. ### Comparing two expressions +``` +x=10 +y=20 +res=`expr $x = $y` +echo $res +``` + +3. ### Match the numbers of characters in two strings +``` +expr alphabet : alpha +``` +4. ### Find the modulus value +``` +expr 20 % 30 +``` +5. ### Extract the substring +``` +a=HelloWorld +b=`expr substr $a 6 10` +echo $b +``` +### Additional Flags and their Functionalities + +|**Flag** |**Description** | +:---|:---| +|`--version`|output version information and exit| +|`--help`|Display this help and exit| + + +For more details: [Expr on Wikipedia](https://en.wikipedia.org/wiki/Expr) \ No newline at end of file diff --git a/docs/Linux-Commands/.recycle/trash/000-the-introduction-command.md b/docs/Linux-Commands/.recycle/trash/000-the-introduction-command.md new file mode 100755 index 0000000..bc31044 --- /dev/null +++ b/docs/Linux-Commands/.recycle/trash/000-the-introduction-command.md @@ -0,0 +1,73 @@ +# 101 Linux commands Open-source eBook + +This is an open-source eBook with 101 Linux commands that everyone should know. No matter if you are a DevOps/SysOps engineer, developer, or just a Linux enthusiast, you will most likely have to use the terminal at some point in your career. + +## Hacktoberfest + +This eBook is made possible thanks to [Hacktoberfest](https://hacktoberfest.digitalocean.com/) and the open source community! + +## About me + +My name is Bobby Iliev, and I have been working as a Linux DevOps Engineer since 2014. I am an avid Linux lover and supporter of the open-source movement philosophy. I am always doing that which I cannot do in order that I may learn how to do it, and I believe in sharing knowledge. + +I think it's essential always to keep professional and surround yourself with good people, work hard, and be nice to everyone. You have to perform at a consistently higher level than others. That's the mark of a true professional. + +For more information, please visit my blog at [https://bobbyiliev.com](https://bobbyiliev.com), follow me on Twitter [@bobbyiliev_](https://twitter.com/bobbyiliev_) and [YouTube](https://www.youtube.com/channel/UCQWmdHTeAO0UvaNqve9udRw). + +### DigitalOcean + +DigitalOcean is a cloud services platform delivering the simplicity developers love and businesses trust to run production applications at scale. + +It provides highly available, secure, and scalable compute, storage, and networking solutions that help developers build great software faster. + +Founded in 2012 with offices in New York and Cambridge, MA, DigitalOcean offers transparent and affordable pricing, an elegant user interface, and one of the largest libraries of open source resources available. + +For more information, please visit [https://www.digitalocean.com](https://www.digitalocean.com) or follow [@digitalocean](https://twitter.com/digitalocean) on Twitter. + +If you are new to DigitalOcean, you can get a free $100 credit and spin up your own servers via this referral link here: + +[Free $100 Credit For DigitalOcean](https://m.do.co/c/2a9bba940f39) + +### DevDojo + +The DevDojo is a resource to learn all things web development and web design. Learn on your lunch break or wake up and enjoy a cup of coffee with us to learn something new. + +Join this developer community, and we can all learn together, build together, and grow together. + +[Join DevDojo](https://devdojo.com?ref=bobbyiliev) + +For more information, please visit [https://www.devdojo.com](https://www.devdojo.com?ref=bobbyiliev) or follow [@thedevdojo](https://twitter.com/thedevdojo) on Twitter. + +## Ebook PDF Generation Tool + +This ebook was generated by [Ibis](https://github.com/themsaid/ibis/) developed by [Mohamed Said](https://github.com/themsaid). + +Ibis is a PHP tool that helps you write eBooks in markdown. + +## Book Cover + +The cover for this ebook was created by [Suhail Kakar](https://twitter.com/SuhailKakar). + +## License + +MIT License + +Copyright (c) 2020 Bobby Iliev + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/docs/Linux-Commands/.recycle/trash/999-wrap-up.md b/docs/Linux-Commands/.recycle/trash/999-wrap-up.md new file mode 100755 index 0000000..1f46fac --- /dev/null +++ b/docs/Linux-Commands/.recycle/trash/999-wrap-up.md @@ -0,0 +1 @@ +999-wrap-up.md diff --git a/docs/Linux-Commands/Archive-Files/015-the-gzip-command.md b/docs/Linux-Commands/Archive-Files/015-the-gzip-command.md new file mode 100755 index 0000000..15cb159 --- /dev/null +++ b/docs/Linux-Commands/Archive-Files/015-the-gzip-command.md @@ -0,0 +1,96 @@ +# The `gzip` command + +The `gzip` command in Linux/Unix is used to compress/decompress data. + +# Usage + +## Compress a file + +**Action:** +--- Compressing a file + +**Details:** +--- Reduce the size of the file by applying compression + +**Command:** +``` +gzip file_name +``` + +## Decompress a file + +**Action:** +--- Decompressing a file + +**Details:** +--- Restore the file's original form in terms of data and size + +**Command:** +``` +gzip -d archive_01.gz +``` + +## Compress multiple files: + +**Action:** +--- Compress multiple files + +**Details:** +--- Compress multiple files into multiple archives + +**Command:** +``` +gzip file_name_01 file_name_02 file_name_03 +``` + +## Decompress multiple files: + +**Action:** +--- Decompress multiple files + +**Details:** +--- Decompress multiple files from multiple archives + +**Command:** +``` +gzip -d archive_01.gz archive_02.gz archive_03.gz +``` + +## Compress a directory: + +**Action:** +--- Compress all the files in a directory + +**Details:** +--- Compress multiple files under a directory in one single archive + +**Command:** +``` +gzip -r directory_name +``` + +## Decompress a directory: + +**Action:** +--- Decompress all the files in a directory + +**Details:** +--- Decompress multiple files under a directory from one single archive + +**Command:** +``` +gzip -dr directory_name +``` + +## Verbose (detailed) output while compressing: + +**Action:** +--- Compress a file in a more verbose manner + +**Details:** +--- Output more information about the action of the command + +**Command:** +``` +gzip -v file_name +``` diff --git a/docs/Linux-Commands/Archive-Files/054-the-zip-command.md b/docs/Linux-Commands/Archive-Files/054-the-zip-command.md new file mode 100755 index 0000000..f489d3d --- /dev/null +++ b/docs/Linux-Commands/Archive-Files/054-the-zip-command.md @@ -0,0 +1,41 @@ +# The `zip` command + +The `zip` command is used to compress files and reduce their size. +It outputs an archive containing one or more compressed files or directories. + +### Examples: + +In order to compress a single file with the `zip` command the syntax would be the following: + +``` +zip myZipFile.zip filename.txt +``` + +This also works with multiple files as well: + +``` +zip multipleFiles.zip file1.txt file2.txt +``` + +If you are compressing a whole directory, don't forget to add the `-r` flag: + +``` +zip -r zipFolder.zip myFolder/ +``` + +### Syntax: + +``` +zip [OPTION] zipFileName filesList +``` + +### Possible options: + +|**Flag** |**Description** | +|:---|:---| +|`-d`|Removes the file from the zip archive. After creating a zip file, you can remove a file from the archive using the `-d` option| +|`-u`|Updates the file in the zip archive. This option can be used to update the specified list of files or add new files to the existing zip file. Update an existing entry in the zip archive only if it has been modified more recently than the version already in the zip archive.| +|`-m`|Deletes the original files after zipping.| +|`-r`|To zip a directory recursively, it will recursively zip the files in a directory. This option helps to zip all the files present in the specified directory.| +|`-x`|Exclude the files in creating the zip| +|`-v`|Verbose mode or print diagnostic version info. Normally, when applied to real operations, this option enables the display of a progress indicator during compression and requests verbose diagnostic info about zip file structure oddities| diff --git a/docs/Linux-Commands/Archive-Files/055-the-unzip-command.md b/docs/Linux-Commands/Archive-Files/055-the-unzip-command.md new file mode 100755 index 0000000..26e2795 --- /dev/null +++ b/docs/Linux-Commands/Archive-Files/055-the-unzip-command.md @@ -0,0 +1,44 @@ +# The `unzip` command + +The `unzip` command extracts all files from the specified ZIP archive to the current directory. + +### Examples: + +In order to extract the files the syntax would be the following: + +``` +unzip myZipFile.zip +``` + +To unzip a ZIP file to a different directory than the current one, don't forget to add the `-d` flag: + +``` +unzip myZipFile.zip -d /path/to/directory +``` + +To unzip a ZIP file and exclude specific file or files or directories from being extracted, don't forget to add the `-x` flag: + +``` +unzip myZipFile.zip -x file1.txt file2.txt +``` + +### Syntax: + +``` +unzip zipFileName [OPTION] [PARAMS] +``` + +### Possible options: + +|**Flag** |**Description** |**Params** | +|:---|:---|:---| +|`-d`|Unzip an archive to a different directory.|/path/to/directory| +|`-x`|Extract the archive but do not extract the specified files.|filename(s)| +|`-j`|Unzip without creating new folders, if the zipped archive contains a folder structure.|-| +|`-l`|Lists the contents of an archive file without extracting it.|-| +|`-n`|Do not overwrite existing files; supply an alternative filename instead.|-| +|`-o`|Overwrite files.|-| +|`-P`|Supplies a password to unzip a protected archive file.|password| +|`-q`|Unzips without writing status messages to the standard output.|-| +|`-t`|Tests whether an archive file is valid.|-| +|`-v`|Displays detailed (verbose) information about the archive without extracting it.|-| diff --git a/docs/Linux-Commands/Archive-Files/063-the-tar-command.md b/docs/Linux-Commands/Archive-Files/063-the-tar-command.md new file mode 100755 index 0000000..d766fbb --- /dev/null +++ b/docs/Linux-Commands/Archive-Files/063-the-tar-command.md @@ -0,0 +1,76 @@ +# The `tar` command + +The `tar` command stands for tape archive, is used to create Archive and extract the Archive files. This command provides archiving functionality in Linux. We can use tar command to create compressed or uncompressed Archive files and also maintain and modify them. + +### Examples: + +1. To create a tar file in abel directory: + +``` +tar -cvf file-14-09-12.tar /home/abel/ +``` + +2. To un-tar a file in the current directory: + +``` + tar -xvf file-14-09-12.tar +``` + +### Syntax: + +``` +tar [options] [archive-file] [file or directory to be archived +``` + + +### Additional Flags and their Functionalities: + +|**Use Flag** |**Description** | +|:---|:---| +|`-c`|Creates Archive | +|`-x`|Extract the archive | +|`-f`|Creates archive with given filename| +|`-t`|Displays or lists files in archived file | +|`-u`|Archives and adds to an existing archive file| +|`-v`|Displays Verbose Information | +|`-A`|Concatenates the archive files | +|`-z`|zip, tells tar command that creates tar file using gzip | +|`-j`|Filter archive tar file using tbzip | +|`w`|Verify a archive file | +|`r`|update or add file or directory in already existed .tar file | +|`-?`|Displays a short summary of the project | +|`-d`|Find the difference between an archive and file system | +|`--usage`|shows available tar options | +|`--version`|Displays the installed tar version | +|`--show-defaults`|Shows default enabled options | + +|**Option Flag** |**Description** | +|:---|:---| +|`--check-device`| Check device numbers during incremental archive| +|`-g`|Used to allow compatibility with GNU-format incremental ackups| +|`--hole-detection`|Used to detect holes in the sparse files| +|`-G`| Used to allow compatibility with old GNU-format incremental backups| +|`--ignore-failed-read`|Don't exit the program on file read errors| +|`--level`|Set the dump level for created archives| +|`-n`|Assume the archive is seekable| +|`--no-check-device`|Do not check device numbers when creating archives| +|`--no-seek`|Assume the archive is not seekable| +|`--occurrence=N`|`Process only the Nth occurrence of each file| +|`--restrict`|`Disable use of potentially harmful options| +|`--sparse-version=MAJOR,MINOR`|Set version of the sparce format to use| +|`-S`|Handle sparse files efficiently.| + +|**Overwright control Flag** |**Description**| +|:---|:---| +|`-k`|Don't replace existing files| +|`--keep-newer-files`|Don't replace existing files that are newer than the archives version| +|`--keep-directory-symlink`|Don't replace existing symlinks| +|`--no-overwrite-dir`|Preserve metadata of existing directories| +|`--one-top-level=DIR`|Extract all files into a DIR| +|`--overwrite`| Overwrite existing files| +|`--overwrite-dir`| Overwrite metadata of directories| +|`--recursive-unlink`| Recursivly remove all files in the directory before extracting| +|`--remove-files`| Remove files after adding them to a directory| +|`--skip-old-files`| Don't replace existing files when extracting| +|`-u`| Remove each file before extracting over it| +|`-w`| Verify the archive after writing it| diff --git a/docs/Linux-Commands/Archive-Files/064-the-gunzip-command.md b/docs/Linux-Commands/Archive-Files/064-the-gunzip-command.md new file mode 100755 index 0000000..8805f0b --- /dev/null +++ b/docs/Linux-Commands/Archive-Files/064-the-gunzip-command.md @@ -0,0 +1,57 @@ +# The `gunzip` command + +The `gunzip` command is an antonym command of [`gzip` command](015-the-gzip-command.md). In other words, it decompresses files deflated by the `gzip` command. + +`gunzip` takes a list of files on its command line and replaces each file whose name ends with _.gz_, _-gz_, _.z_, _-z_, or *\_z* (ignoring case) and which begins with the correct magic number with an uncompressed file without the original extension. `gunzip` also recognizes the special extensions *.tgz* and *.taz* as shorthands for *.tar.gz* and *.tar.Z* respectively. + +### Examples: + +1. Uncompress a file + +``` +gunzip filename.gz +``` + +2. Recursively uncompress content inside a directory, that match extension (suffix) compressed formats accepted by `gunzip`: + +``` +gunzip -r directory_name/ +``` + +3. Uncompress all files in the current/working directory whose suffix match *.tgz*: + +``` +gunzip -S .tgz * +``` + +4. List compressed and uncompressed sizes, compression ratio and uncompressed name of input compressed file/s: + +``` +gunzip -l file_1 file_2 +``` + +### Syntax: + +``` +gunzip [ -acfhklLnNrtvV ] [-S suffix] [ name ... ] +``` + +### Video tutorial about using gzip, gunzip and tar commands: + +[This video](https://www.youtube.com/watch?v=OBtG8zfVwuI) shows how to compress and decompress in a Unix shell. It uses `gunzip` as decompression command. + +### Additional Flags and their Functionalities: + +|**Short Flag**|**Long Flag**|**Description**| +|:---|:---|:---| +|-c|--stdout|write on standard output, keep original files unchanged| +|-h|--help|give help information| +|-k|--keep|keep (don't delete) input files| +|-l|--list|list compressed file contents| +|-q|--quiet|suppress all warnings| +|-r|--recursive|operate recursively on directories| +|-S|--suffix=SUF|use suffix SUF on compressed files| +||--synchronous|synchronous output (safer if system crashes, but slower)| +|-t|--test|test compressed file integrity| +|-v|--verbose|verbose mode| +|-V|--version|display version number| \ No newline at end of file diff --git a/docs/Linux-Commands/Disk-Management/010-the-df-command.md b/docs/Linux-Commands/Disk-Management/010-the-df-command.md new file mode 100755 index 0000000..4941e8e --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/010-the-df-command.md @@ -0,0 +1,105 @@ +# The `df` command +The `df` command in Linux/Unix is used to show the disk usage & information. +`df` is an abbreviation for "disk free". + +`df` displays the amount of disk space available on the file system containing each file name argument. If no file name is given, the space available on all currently mounted file systems is shown. + +### Syntax +``` +df [OPTION]... [FILE]... +``` + +### Options +|**Short Flag**|**Long Flag**|**Description**| +|:--|:--|:--| +|`-a`|`--all`|Include pseudo, duplicate, inaccessible file systems.| +|`-B`|`--block-size=SIZE`|Scale sizes by SIZE before printing them; e.g., `-BM` prints sizes in units of 1,048,576 bytes; see SIZE format below.| +|`-h`|`--human-readable`|Print sizes in powers of 1024 (e.g., 1023M).| +|`-H`|`--si`|Print sizes in powers of 1000 (e.g., 1.1G).| +|`-i`|`--inodes`|List inode information instead of block usage.| +|`-k`|
-
|Like `--block-size=1K`.| +|`-l`|`--local`|Limit listing to local file systems.| +|
-
|`--no-sync`|Do not invoke `sync` before getting usage info (default).| +|
-
|`--output[=FIELD_LIST]`|Use the output format defined by `FIELD_LIST`, or print all fields if FIELD_LIST is omitted.| +|`-P`|`--portability`|Use the `POSIX` output format| +|
-
|`--sync`|Invoke sync before getting usage info.| +|
-
|`--total`|Elide all entries insignificant to available space, and produce a grand total.| +|`-t`|`--type=TYPE`|Limit listing to file systems of type `TYPE`.| +|`-T`|`--print-type`|Print file system type.| +|`-x`|`--exclude-type=TYPE`|Limit listing to file systems not of type `TYPE`.| +|`-v`|
-
|Ignored; included for compatibility reasons.| +|
-
|`--help`|Display help message and exit.| +|
-
|`--version`|Output version information and exit.| + +### Examples: +1. Show available disk space +**Action:** +--- Output the available disk space and where the directory is mounted + +**Details:** +--- Outputted values are not human-readable (are in bytes) + +**Command:** +``` +df +``` + +2. Show available disk space in human-readable form +**Action:** +--- Output the available disk space and where the directory is mounted + +**Details:** +--- Outputted values ARE human-readable (are in GBs/MBs) + +**Command:** +``` +df -h +``` + +3. Show available disk space for the specific file system +**Action:** +--- Output the available disk space and where the directory is mounted + +**Details:** +--- Outputted values are only for the selected file system + +**Command:** +``` +df -hT file_system_name +``` + +4. Show available inodes +**Action:** +--- Output the available inodes for all file systems + +**Details:** +--- Outputted values are for inodes and not available space + +**Command:** +``` +df -i +``` + +5. Show file system type +**Action:** +--- Output the file system types + +**Details:** +--- Outputted values are for all file systems + +**Command:** +``` +df -T +``` + +6. Exclude file system type from the output +**Action:** +--- Output the information while excluding the chosen file system type + +**Details:** +--- Outputted values are for all file systems EXCEPT the chosen file system type + +**Command:** +``` +df -x file_system_type +``` diff --git a/docs/Linux-Commands/Disk-Management/084-the-du-command.md b/docs/Linux-Commands/Disk-Management/084-the-du-command.md new file mode 100755 index 0000000..cdd97fb --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/084-the-du-command.md @@ -0,0 +1,37 @@ +# The `du` command + +The `du` command, which is short for `disk usage` lets you retrieve information about disk space usage information in a specified directory. In order to customize the output according to the information you need, this command can be paired with the appropriate options or flags. + +### Examples: + +1. To show the estimated size of sub-directories in the current directory: + +``` +du +``` + +2. To show the estimated size of sub-directories inside a specified directory: + +``` +du {PATH_TO_DIRECTORY} +``` + +### Syntax: + +``` +du [OPTION]... [FILE]... +du [OPTION]... --files0-from=F +``` + +### Additional Flags and their Functionalities: + +*Note: This does not include an exhaustive list of options.* + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-a`|`--all`|Includes information for both files and directories| +|`-c`|`--total`|Provides a grand total at the end of the list of files/directories| +|`-d`|`--max-depth=N`|Provides information up to `N` levels from the directory where the command was executed| +|`-h`|`--human-readable`|Displays file size in human-readable units, not in bytes| +|`-s`|`--summarize`|Display only the total filesize instead of a list of files/directories| + diff --git a/docs/Linux-Commands/Disk-Management/104-the-lsblk-command.md b/docs/Linux-Commands/Disk-Management/104-the-lsblk-command.md new file mode 100755 index 0000000..1259313 --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/104-the-lsblk-command.md @@ -0,0 +1,118 @@ +# The ``lsblk`` command + +## Summary +The ``lsblk`` command displays the block and loop devices on the system. It is especially useful when you want to format disks, write filesystems, check the filesystem and know the mount point of a device. + + +## Examples + +1. Basic usage is fairly simple - just execute 'lsblk' sans any option. +``` +lsblk +``` + +2. Make lsblk display empty devices as well +``` +lsblk -a +``` + +3. Make lsblk print size info in bytes +``` +lsblk -b +``` + +4. Make lsblk print zone model for each device +``` +lsblk -z +``` + +5. Make lsblk skip entries for slaves +``` +lsblk -d +``` + +6. Make lsblk use ascii characters for tree formatting +``` +lsblk -i +``` + +7. Make lsblk display info about device owner, group, and mode +``` +lsblk -m +``` + +8. Make lsblk output select columns + +``` +lsblk -o NAME,SIZE +``` + +## Syntax +``` +lsblk [options] [ ...] +``` + +## Reading information given by ``lsblk`` +On running ``lsblk`` with no flags or command-line arguments, it writes general disk information to the STDOUT. +Here is a table that interpretes that information: + +| Column Name | Meaning | Interpretation | +|:-----------:|:----------------------------------|:------------------------------------------------------------| +| NAME | Name of the device. | Shows name of the device. | +| RM | Removable. | Shows 1 if the device is removable, 0 if not. | +| SIZE | Size of the device. | Shows size of the device. | +| RO | Read-Only. | Shows 1 if read-only, 0 if not. | +| TYPE | The type of block or loop device. | Shows ``disk`` for entire disk and ``part`` for partitions. | +| MOUNTPOINTS | Where the device is mounted. | Shows where the device is mounted. Empty if not mounted. | + +## Reading information of a specific device +``lsblk`` can display information of a specific device when the device's absolute path is passed to it. +For example, ``lsblk`` command for displaying the information of the ``sda`` disk is: +``` +lsblk /dev/sda +``` + +## Useful flags for ``lsblk`` +Here is a table that show some of the useful flags that can be used with lsblk + +| **Short Flag** | **Long Flag** | **Description** | +|:--------------------------:|:-----------------------|:---------------------------------------------| +| ``-a`` | ``--all`` | `lsblk` does not list empty devices by default. This option disables this restriction. | +| ``-b`` | ``--bytes`` | Print the SIZE column in bytes rather than in human-readable format. | +| ``-d`` | ``--nodeps`` | Don't print device holders or slaves. | +| ``-D`` | ``--discard`` | Print information about the discard (TRIM, UNMAP) capabilities for each device. | +| ``-E`` | ``--dedup column`` | Use column as a de-duplication key to de-duplicate output tree. If the key is not available for the device, or the device is a partition and parental whole-disk device provides the same key than the device is always printed.| +| ``-e`` | ``--exclude list`` | xclude the devices specified by a comma-separated list of major device numbers. Note that RAM disks (major=1) are excluded by default. The filter is applied to the top-level devices only.| +| ``-f`` | ``--fs`` | Displays information about filesystem. | +| ``-h`` | ``--help`` | Print a help text and exit.| +| ``-l`` | ``--include list`` | Displays all the information in List Format. | +| ``-J`` | ``--json`` | Displays all the information in JSON Format. | +| ``-l`` | ``--list`` | Displays all the information in List Format. | +| ``-m`` | ``--perms`` | Displays info about device owner, group and mode. | +| ``-M`` | ``--merge`` | Group parents of sub-trees to provide more readable output for RAIDs and Multi-path devices. The tree-like output is required.| +| ``-n`` | ``--noheadings`` | Do not print a header line. | +| ``-o`` | ``--output list`` | Specify which output columns to print. Use `--help` to get a list of all supported columns. | +| ``-O`` | ``--output-all`` | Displays all available columns. | +| ``-p`` | ``--paths`` | Displays absolute device paths. | +| ``-P`` | ``--pairs`` | Use key="value" output format. All potentially unsafe characters are hex-escaped (\x) | +| ``-r`` | ``--raw`` | Use the raw output format. All potentially unsafe characters are hex-escaped (\x) in NAME, KNAME, LABEL, PARTLABEL and MOUNTPOINT columns.| +| ``-S`` | ``--scsi`` | Output info about SCSI devices only. All partitions, slaves and holder devices are ignored.| +| ``-s`` | ``--inverse`` | Print dependencies in inverse order. | +| ``-t`` | ``--topology`` | Output info about block device topology. This option is equivalent to "-o NAME,ALIGNMENT,MIN-IO,OPT-IO,PHY-SEC,LOG-SEC,ROTA,SCHED,RQ-SIZE".| +| ``-T`` | ``--tree[=column]`` | Displays all the information in Tree Format. | +| ``-V`` | ``--version`` | Output version information and exit. | +| ``-w`` | ``--width`` |pecifies output width as a number of characters. The default is the number of the terminal columns, and if not executed ona terminal, then output width is not restricted at all by default.| +| ``-x`` | ``--sort [column]`` | Sort output lines by column. This option enables `--list` output format by default. It is possible to use the option `--tree` to force tree-like output and than the tree branches are sorted by the column.| +| ``-z`` | ``--zoned`` | Print the zone model for each device. | +| ``-`` | ``--sysroot directory``| Gather data for a Linux instance other than the instance from which the lsblk command is issued. The specified directory is the system root of the Linux instance to be inspected.| + +## Exit Codes +Like every Unix / Linux Program, ``lslbk`` returns an exit code to the environment. +Here is a table of all the exit codes. + +| Exit Code | Meaning | +|:---------:|:-----------------------------------------------------------| +| 0 | Exit with success. | +| 1 | Exit with failure. | +| 32 | Specified device(s) not found. | +| 64 | Some of the specified devices were found while some not. | diff --git a/docs/Linux-Commands/Disk-Management/116-the-mount-command.md b/docs/Linux-Commands/Disk-Management/116-the-mount-command.md new file mode 100755 index 0000000..8626bea --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/116-the-mount-command.md @@ -0,0 +1,44 @@ + +# The `mount` command + +The `mount` command is used to mount 'attach' a filesystem and make it accessible by an existing directory structure tree. +### Examples: + +1. Displays version information: + +``` +mount -V +``` + +2. Attaching filesystem found on device and of type type at the directory dir: + +``` +mount -t type device dir +``` + +### Syntax Forms: + +``` +mount [-lhV] +``` +``` +mount -a [-fFnrsvw] [-t vfstype] [-O optlist] +``` +``` +mount [-fnrsvw] [-t fstype] [-o options] device dir +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-h`|
`--help`
|Dispaly a help message and exists| +|`-n`|
`--no-mtab`
|Mount without writing in /etc/mtab| +|`-a`|
`--all`
|Mount all filesystems (of the given types) mentioned in fstab| +|`-r`|`--read-only`|Mount the filesystem read-only| +|`-w`|`--rw`|Mount the filesystem as read/write.| +|`-M`|`--move`|Move a subtree to some other place.| +|`-B`|`--bind`|Remount a subtree somewhere else *(so that its contents are available in both places)*.| + + + diff --git a/docs/Linux-Commands/Disk-Management/120-the-fdisk-command.md b/docs/Linux-Commands/Disk-Management/120-the-fdisk-command.md new file mode 100755 index 0000000..d138847 --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/120-the-fdisk-command.md @@ -0,0 +1,50 @@ +# The `fdisk` command + +The `fdisk` command is used for controlling the disk partition table and making changes to it and this is a list of some of options provided by it : +- Organize space for new drives. +- Modify old drives. +- Create space for new partitions. +- Move data to new partitions. + + +### Examples: + +1. To view basic details about all available partitions on the system: + +``` +fdisk -l +``` + +2. To show the size of the partition: + +``` +fdisk -s /dev/sda +``` + +3. To view the help message and all options of the command: +``` +fdisk -h +``` + +### Syntax: + +``` +fdisk [options] device +``` + +### Some of the command options: + +On writing the following command +``` +fdisk /dev/sdb +``` +the following window appears : +![Options](https://media.geeksforgeeks.org/wp-content/uploads/20190219152451/Screenshot-711.png) +and then you type m which will show you all options you need such as creating new partition and deleting a partition as in the following picture : +![Options](https://media.geeksforgeeks.org/wp-content/uploads/20190219153114/Screenshot-741.png) + + + + + + diff --git a/docs/Linux-Commands/Disk-Management/128-the-parted-command.md b/docs/Linux-Commands/Disk-Management/128-the-parted-command.md new file mode 100755 index 0000000..5f58570 --- /dev/null +++ b/docs/Linux-Commands/Disk-Management/128-the-parted-command.md @@ -0,0 +1,75 @@ +# The `parted` command + +The `parted` command is used to manage hard disk partitions on Linux. It can be used to add, delete, shrink and extend disk partitions along with the file systems located on them. +You will need root access to the system to run `parted` commands. + +**NOTE:** Parted writes the changes immediately to your disk, be careful when you are modifying the disk partitions. +### Examples: + +1. Displays partition layout of all block devices: +``` +sudo parted -l +``` + +2. Display partition table of a specific `disk` +``` +sudo parted disk print +``` + +Examples of `disk` are /dev/sda, /dev/sdb + +3. Create a new disk label of `label-type` for a specific disk +``` +sudo parted mklabel disk label-type +``` + +`label-type` can take values "aix", "amiga", "bsd", "dvh", "gpt", "loop", "mac", "msdos", "pc98", or "sun"
+ +4. Create a new partition in a specific `disk` of type `part-time`, file system is `fs-type` and of size `size` Mb. +``` +sudo parted disk mkpart part-time fs-type 1 size +``` + +`part-time` can take values "primary", "logical", "extended".
+`fs-type` is optional. It can take values "btrfs", "ext2", "ext3", "ext4", "fat16", "fat32", "hfs", "hfs+", "linux-swap", "ntfs", "reiserfs", "udf", or "xfs"
+`size` has to less than the total size of the specified disk. To create a partition of size 50Mb, will take the value of 50 + +5. `parted` can also be run in an interactive format. Operations to manage the disk partitions can be performed by entering appropriate commands in the interactive session. + `help` command in the interactive session shows a list of all possible disk management operations which can be performed. +``` + $ sudo parted + GNU Parted 3.3 + Using /dev/sda + Welcome to GNU Parted! Type 'help' to view a list of commands. + (parted) print # prints the partition table of the default selected disk - /dev/sda + Model: ATA VBOX HARDDISK (scsi) + Disk /dev/sda: 53.7GB + Sector size (logical/physical): 512B/512B + Partition Table: msdos + Disk Flags: + + Number Start End Size Type File system Flags + 1 1049kB 53.7GB 53.7GB primary ext4 boot + + (parted) select /dev/sdb # change the current disk on which operations have to be performed + Using /dev/sdb + (parted) quit # exit the interactive session +``` + +### Syntax Forms: +``` +parted [options] [device [command [options...]...]] +``` + +### Options: +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|-h|--help|displays a help message listing all possible `commands [options]`| +|-l|--list|lists partition layout on all block devices| +|-m|--machine|displays machine parseable output| +|-v|--version|displays the version| +|-a|--align|set alignment type for newly created partition. It can take the following values:
`none`: Use the minimum alignment allowed by the disk type
`cylinder`: Align partitions to cylinders
`minimal`: Use minimum alignment as given by the disk topology information
`optimal`: Use optimum alignment as given by the disk topology information| + + + + diff --git a/docs/Linux-Commands/Networking/041-the-ifconfig-command.md b/docs/Linux-Commands/Networking/041-the-ifconfig-command.md new file mode 100755 index 0000000..b44926f --- /dev/null +++ b/docs/Linux-Commands/Networking/041-the-ifconfig-command.md @@ -0,0 +1,101 @@ +# The `ifconfig` command + +`ifconfig` is used to configure the kernel-resident network interfaces. It is used at boot time to set up interfaces as necessary. After that, it is usually only needed when debugging or when system tuning is needed. + + +If no arguments are given, `ifconfig` displays the status of the currently active interfaces. If a single interface argument is given, it displays the status of the given interface only; if a single -a argument is given, it displays the status of all interfaces, even those that are down. Otherwise, it configures an interface. +### Syntax: + +``` +ifconfig [-v] [-a] [-s] [interface] +ifconfig [-v] interface [aftype] options +``` + +### Examples: + +1. To display the currently active interfaces: + +``` +ifconfig +``` + +2. To show all interfaces which are currently active, even if down: + +``` +ifconfig -a +``` + +3. To show all the error conditions: + +``` +ifconfig -v +``` + +4. To show a short list: + +``` +ifconfig -s +``` + +5. To display details of the specific network interface (say `eth0`): +``` +ifconfig eth0 +``` + +6. To activate the driver for a interface (say `eth0`): +``` +ifconfig eth0 up +``` + +7. To deactivate the driver for a interface (say `eth0`): +``` +ifconfig eth0 down +``` + +8. To assign a specific IP address to a network interface (say `eth0`): +``` +ifconfig eth0 10.10.1.23 +``` + +9. To change MAC(Media Access Control) address of a network interface (say `eth0`): +``` +ifconfig eth0 hw ether AA:BB:CC:DD:EE:FF +``` +10. To define a netmask for a network interface (say `eth0`): +``` +ifconfig eth0 netmask 255.255.255.224 +``` + +11. To enable promiscous mode on a network interface (say `eth0`): +``` +ifconfig eth0 promisc +``` +In normal mode, when a packet is received by a network card, it verifies that it belongs to itself. If not, it drops the packet normally. However, in the promiscuous mode, it accepts all the packets that flow through the network card. + +12. To disable promiscous mode on a network interface (say `eth0`): +``` +ifconfig eth0 -promisc +``` + +13. To set the maximum transmission unit to a network interface (say `eth0`): +``` +ifconfig eth0 mtu 1000 +``` +The MTU allows you to set the limit size of packets that are transmitted on an interface. The MTU is able to handle a maximum number of octets to an interface in one single transaction. + +14. To add additional IP addresses to a network interface, you can configure a network alias to the network interface: +``` +ifconfig eth0:0 10.10.1.24 +``` +Please note that the alias network address is in the same subnet mask of the network interface. For example, if your eth0 network ip address is `10.10.1.23`, then the alias ip address can be `10.10.1.24`. Example of an invalid IP address is `10.10.2.24` since the interface subnet mask is `255.255.255.224` + +15. To remove a network alias: +``` +ifconfig eth0:0 down +``` +Remember that for every scope (i.e. same net with address/netmask combination) all aiases are deleted, if you delete the first alias. +### Help Command +Run below command to view the complete guide to `ifconfig` command. +``` +man ifconfig +``` diff --git a/docs/Linux-Commands/Networking/045-the-wget-command.md b/docs/Linux-Commands/Networking/045-the-wget-command.md new file mode 100755 index 0000000..0f9e287 --- /dev/null +++ b/docs/Linux-Commands/Networking/045-the-wget-command.md @@ -0,0 +1,51 @@ +# The `wget` command + +The `wget` command is used for downloading files from the Internet. It supports downloading files using HTTP, HTTPS and FTP protocols. It allows you to download several files at once, download in the background, resume downloads, limit the bandwidth, mirror a website, and much more. + +## Syntax + +The `wget` syntax requires you to define the downloading options and the URL the to be downloaded file is coming from. + +```bash +$ wget [options] [URL] +``` + +### Examples + +In this example we will download the Ubuntu 20.04 desktop iso file from different sources. Go over to your terminal or open a new one and type in the below `wget`. This will stat the download. The download may take a few minutes to complete. + +1. Starting a regular download + +```bash +wget https://releases.ubuntu.com/20.04/ubuntu-20.04.3-desktop-amd64.iso +``` + +2. You can resume a download using the `-c` option + +```bash +wget -c https://mirrors.piconets.webwerks.in/ubuntu-mirror/ubuntu-releases/20.04.3/ubuntu-20.04.3-desktop-amd64.iso +``` + +3. To download in the background, use the `-b` option + +```bash +wget -b https://mirrors.piconets.webwerks.in/ubuntu-mirror/ubuntu-releases/20.04.3/ubuntu-20.04.3-desktop-amd64.iso +``` + +## More options + +On top of downloading, `wget` provides many more features, such as downloading multiple files, dowloading in the background, limiting download bandwith and resuming stopped downloads. View all `wget` options in its man page. + +```bash +man wget +``` + +### Additional Flags and their Functionalities + +| **Short Flag** | **Description** | +| -------------- | ----------------------------------------------------------------------------- | +| `-v` | prints version of the wget available on your system | +| `-h` | print help message displaying all the possible options | +| `-b` | This option is used to send a process to the background as soon as it starts. | +| `-t` | This option is used to set number of retries to a specified number of times | +| `-c` | This option is used to resume a partially downloaded file | diff --git a/docs/Linux-Commands/Networking/046-the-curl-command.md b/docs/Linux-Commands/Networking/046-the-curl-command.md new file mode 100755 index 0000000..caa4ea9 --- /dev/null +++ b/docs/Linux-Commands/Networking/046-the-curl-command.md @@ -0,0 +1,51 @@ +# The `curl` command + +In linux, `curl` is a tool to transfer data from or to a server, using one of the supported protocols(DICT, FILE ,FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). + +## Example : + +```bash +$ curl example.com +``` + +The command will print the source code of the example.com homepage in the terminal window. + +## The syntax of the `curl` command is : + +```bash +$ curl [options...] +``` + +## Options : + +Options start with one or two dashes. Many of the options require an additional value next to them. + +The short "single-dash" form of the options, `-d` for example, may be used with or without a space between it and its value, although a space is a recommended separator. The long "double-dash" form, `-d`, `--data` for example, requires a space between it and its value. + +Short version options that don't need any additional values can be used immediately next to each other, like for example you can specify all the options `-O`, `-L` and `-v` at once as `-OLv`. + +In general, all boolean options are enabled with `--option` and yet again disabled with `--no-option`. That is, you use the exact same option name but prefix it with `no-`. However, in this list we mostly only list and show the `--option` version of them. (This concept with `--no` options was added in 7.19.0. Previously most options were toggled on/off through repeated use of the same command line option.) + +## Installation: + +The curl command comes with most of the Linux distributions. But, if the system does not carry the curl by default. You need to install it manually. To install the curl, execute the following commands: + +Update the system by executing the following commands: + +```bash +$ sudo apt update +$ sudo apt upgrade +``` +Now, install the curl utility by executing the below command: + +```bash +$ sudo apt install curl +``` + +Verify the installation by executing the below command: + +```bash +$ curl -version +``` + +The above command will display the installed version of the curl command. diff --git a/docs/Linux-Commands/Networking/067-the-netstat-command.md b/docs/Linux-Commands/Networking/067-the-netstat-command.md new file mode 100755 index 0000000..d983379 --- /dev/null +++ b/docs/Linux-Commands/Networking/067-the-netstat-command.md @@ -0,0 +1,60 @@ +# The `netstat` command + +The term `netstat` stands for Network Statistics. In layman’s terms, netstat command displays the current network connections, networking protocol statistics, and a variety of other interfaces. + +Check if you have `netstat` on your PC: + +``` +netstat –v +``` + + +If you don't have `netstat` installed on your PC, you can install it with the following command: + +``` +sudo apt install net-tools +``` + +### You can use `netstat` command for some use cases given below: + +- `Netstat` command with `-nr` flag shows the routing table detail on the terminal. + +Example: + +``` +netstat -nr +``` + +- `Netstat` command with `-i` flag shows statistics for the currently configured network interfaces. +This command will display the first 10 lines of file `foo.txt` . + +Example: + +``` +netstat -i +``` + +- `Netstat` command with `-tunlp` will gives a list of networks, their current states, and their associated ports. + +Example: + +``` +netstat -tunlp +``` + +- You can get the list of all TCP port connection by using `-at` with `netstat`. + +``` +netstat -at +``` + +- You can get the list of all UDP port connection by using `-au` with `netstat`. +``` +netstat -au +``` + +- You can get the list of all active connection by using `-l` with `netstat`. + +``` +netstat -l +``` diff --git a/docs/Linux-Commands/Networking/085-the-ping-command.md b/docs/Linux-Commands/Networking/085-the-ping-command.md new file mode 100755 index 0000000..58faaee --- /dev/null +++ b/docs/Linux-Commands/Networking/085-the-ping-command.md @@ -0,0 +1,59 @@ +# The `ping` command + +The `ping` (Packet Internet Groper) command is a network utility used to check network connectivity between a host and a server or another host. It sends ICMP (Internet Control Message Protocol) echo requests to a specified IP address or URL and measures the time it takes to receive a response. This time delay is referred to as "latency." Ping is a fundamental tool for network troubleshooting and monitoring. + +## Understanding Latency + +Latency, in the context of networking, is the time delay between sending a packet and receiving a response. + +When you use the `ping` command, it measures the latency by sending a series of packets to the target host and calculating the time it takes for each packet to complete the round trip. The latency is typically measured in milliseconds (ms). Understanding latency is essential because: + +- **Network Performance**: Lower latency means faster data transmission and more responsive network connections, which is critical for real-time applications. + +- **Troubleshooting**: High latency can indicate network congestion, packet loss, or connectivity issues that need attention. + +- **Quality of Service (QoS)**: Service providers and network administrators use latency metrics to ensure that network services meet quality standards. + +The basic ping syntax includes ping followed by a hostname, a name of a website, or the exact IP address. + +``` +ping [option] [hostname] or [IP address] +``` + +### Examples: + +1. To get ping version installed on your system. + +``` +sudo ping -v +``` + +2. To check whether a remote host is up, in this case, google.com, type in your terminal: + +``` +ping google.com +``` + +3. Controlling the number of packets to send: +Earlier we did not define the number of packets to send to the server/host by using -c option we can do so. + + ``` +ping -c 5 google.com +``` + +4. Controlling the size of the packet: +Earlier a default sized packets were sent to a host but we can send light and heavy packet by using +-s option. + +``` +ping -s 40 -c 5 google.com +``` + +5. Changing the time interval between ping packets: +By default ping wait for 1 sec to send next packet we can change this time by using -i option. + +``` +ping -i 2 google.com +``` + + diff --git a/docs/Linux-Commands/Networking/089-the-ssh-command.md b/docs/Linux-Commands/Networking/089-the-ssh-command.md new file mode 100755 index 0000000..a65b98e --- /dev/null +++ b/docs/Linux-Commands/Networking/089-the-ssh-command.md @@ -0,0 +1,86 @@ +# The `ssh` command + +The `ssh` command in Linux stands for "Secure Shell". It is a protocol used to securely connect to a remote server/system. ssh is more secure in the sense that it transfers the data in encrypted form between the host and the client. ssh runs at TCP/IP port 22. + +### Examples: + +1. Use a Different Port Number for SSH Connection: + +``` +ssh test.server.com -p 3322 +``` + +2. -i ssh to remote server using a private key? + +``` +ssh -i private.key user_name@host +``` + +3. -l ssh specifying a different username + +``` +ssh -l alternative-username sample.ssh.com +``` + +### Syntax: + +``` +ssh user_name@host(IP/Domain_Name) +``` +``` +ssh -i private.key user_name@host +``` +``` +ssh sample.ssh.com ls /tmp/doc +``` + + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-1`|Forces ssh to use protocol SSH-1 only.| +|`-2`|Forces ssh to use protocol SSH-2 only.| +|`-4`|Allows IPv4 addresses only.| +|`-A`|Authentication agent connection forwarding is enabled..| +|`-a`|Authentication agent connection forwarding is disabled.| +|`-B bind_interface`|Bind to the address of bind_interface before attempting to connect to the destination host. This is only useful on systems with more than one address.| +|`-b bind_address`|Use bind_address on the local machine as the source address of the connection. Only useful on systems with more than one address. +|`-C`|Compresses all data (including stdin, stdout, stderr, and data for forwarded X11 and TCP connections) for a faster transfer of data.| +|`-c cipher_spec`|Selects the cipher specification for encrypting the session.| +|`-D [bind_address:]port`|Dynamic application-level port forwarding. This allocates a socket to listen to port on the local side. When a connection is made to this port, the connection is forwarded over the secure channel, and the application protocol is then used to determine where to connect to from the remote machine.| +|`-E log_file`|Append debug logs instead of standard error.| +|`-e escape_char`|Sets the escape character for sessions with a pty (default: ‘~’). The escape character is only recognized at the beginning of a line. The escape character followed by a dot (‘.’) closes the connection; followed by control-Z suspends the connection; and followed by itself sends the escape character once. Setting the character to “none” disables any escapes and makes the session fully transparent.| +|`-F configfile`|Specifies a per-user configuration file. The default for the per-user configuration file is ~/.ssh/config.| +|`-f`|Requests ssh to go to background just before command execution.| +|`-G`|Causes ssh to print its configuration after evaluating Host and Match blocks and exit.| +|`-g`|Allows remote hosts to connect to local forwarded ports.| +|`-I pkcs11`|Specify the PKCS#11 shared library ssh should use to communicate with a PKCS#11 token providing keys.| +|`-i identity_file`|A file from which the identity key (private key) for public key authentication is read.| +|`-J [user@]host[:port]`|Connect to the target host by first making a ssh connection to the pjump host[(/iam/jump-host) and then establishing a TCP forwarding to the ultimate destination from there.| +|`-K`|Enables GSSAPI-based authentication and forwarding (delegation) of GSSAPI credentials to the server.| +|`-k`|Disables forwarding (delegation) of GSSAPI credentials to the server.| +|`-L [bind_address:]port:host:hostport`, `-L [bind_address:]port:remote_socket`, `-L local_socket:host:hostport`, `-L local_socket:remote_socket`|Specifies that connections to the given TCP port or Unix socket on the local (client) host are to be forwarded to the given host and port, or Unix socket, on the remote side. This works by allocating a socket to listen to either a TCP port on the local side, optionally bound to the specified bind_address, or to a Unix socket. Whenever a connection is made to the local port or socket, the connection is forwarded over the secure channel, and a connection is made to either host port hostport, or the Unix socket remote_socket, from the remote machine.| +|`-l login_name`|Specifies the user to log in as on the remote machine.| +|`-M`|Places the ssh client into “master” mode for connection sharing. Multiple -M options places ssh into “master” mode but with confirmation required using ssh-askpass before each operation that changes the multiplexing state (e.g. opening a new session).| +|`-m mac_spec`|A comma-separated list of MAC (message authentication code) algorithms, specified in order of preference.| +|`-N`|Do not execute a remote command. This is useful for just forwarding ports.| +|`-n`|Prevents reading from stdin.| +|`-O ctl_cmd`|Control an active connection multiplexing master process. When the -O option is specified, the ctl_cmd argument is interpreted and passed to the master process. Valid commands are: “check” (check that the master process is running), “forward” (request forwardings without command execution), “cancel” (cancel forwardings), “exit” (request the master to exit), and “stop” (request the master to stop accepting further multiplexing requests).| +|`-o`|Can be used to give options in the format used in the configuration file. This is useful for specifying options for which there is no separate command-line flag.| +|`-p`, `--port PORT`|Port to connect to on the remote host.| +|`-Q query_option`|Queries ssh for the algorithms supported for the specified version 2. The available features are: cipher (supported symmetric ciphers), cipher-auth (supported symmetric ciphers that support authenticated encryption), help (supported query terms for use with the -Q flag), mac (supported message integrity codes), kex (key exchange algorithms), kex-gss (GSSAPI key exchange algorithms), key (keytypes), key-cert (certificate key types), key-plain (non-certificate key types), key-sig (all keytypes and signature algorithms), protocol-version (supported SSH protocol versions), and sig (supported signature algorithms). Alternatively, any keyword from ssh_config(5) or sshd_config(5) thattakes an algorithm list may be used as an alias for the corresponding query_option.| +|`-q`| Qiet mode. Causes most warning and diagnostic messages to be suppressed.| +|`-R [bind_address:]port:host:hostport, -R [bind_address:]port:local_socket, -R remote_socket:host:hostport, -R remote_socket:local_socket, -R [bind_address:]port`|Specifies that connections to the given TCP port or Unix socket on the remote (server) host are to be forwarded to the local side.| +|`-S ctl_path`|Specifies the location of a control socket for connection sharing, or the string “none” to disable connection sharing.| +|`-s`|May be used to request invocation of a subsystem on the remote system. Subsystems facilitate the use of SSH as a secure transport for other applications (e.g. sftp(1)). The subsystem is specified as the remote command.| +|`-T`| Disable pseudo-terminal allocation.| +|`-t`|Force pseudo-terminal allocation. This can be used to execute arbitrary screen-based programs on a remote machine, which can be very useful, e.g. when implementing menu services. Multiple -t options force tty allocation, even if ssh has no local tty. +|`-V`|Display the version number.| +|`-v`|Verbose mode. It echoes everything it is doing while establishing a connection. It is very useful in the debugging of connection failures.| +|`-W host:port`|Requests that standard input and output on the client be forwarded to host on port over the secure channel. Implies -N, -T, ExitOnForwardFailure and ClearAllForwardings, though these can be overridden in the configuration file or using -o command line options.| +|`-w local_tun[remote_tun]`|Requests tunnel device forwarding with the specified tun devices between the client (local_tun) and the server (remote_tun). The devices may be specified by numerical ID or the keyword “any”, which uses the next available tunnel device. If remote_tun is not specified, it defaults to “any”. If the Tunnel directive is unset, it will be set to the default tunnel mode, which is “point-to-point”. If a different Tunnel forwarding mode it desired, then it should be specified before -w.| +|`-X`|Enables X11 forwarding (GUI Forwarding).| +|`-x`|Disables X11 forwarding (GUI Forwarding).| +|`-Y`|Enables trusted X11 Forwarding.| +|`-y`|Send log information using the syslog system module. By default this information is sent to stderr.| diff --git a/docs/Linux-Commands/Networking/133-the-nslookup-command.md b/docs/Linux-Commands/Networking/133-the-nslookup-command.md new file mode 100755 index 0000000..c52a8c2 --- /dev/null +++ b/docs/Linux-Commands/Networking/133-the-nslookup-command.md @@ -0,0 +1,46 @@ +# The `nslookup` command + +The `nslookup` command is a network administration command-line tool for querying the Domain Name System (DNS) to obtain domain name or IP address mapping or any other specific DNS record. + +## Syntax + +``` +nslookup [options] [host] +``` + +## Options +Some popular option flags include: + +``` +-domain=[domain-name] Change the default DNS name. +-debug Show debugging information. +-port=[port-number] Specify the port for queries. The default port number is 53. +-timeout=[seconds] Specify the time allowed for the server to respond. +-type=a View information about the DNS A address records. +-type=any View all available records. +-type=hinfo View hardware-related information about the host. +-type=mx View Mail Exchange server information. +-type=ns View Name Server records. +-type=ptr View Pointer records. Used in reverse DNS lookups. +-type=soa View Start of Authority records. +``` + +## Few Examples: +1. Query DNS Server +``` +nslookup www.google.com +``` + +2. Specify a port to query +``` +nslookup -port=53 www.google.com +``` + +3. Get the MX Record +``` +nslookup -type=mx google.com +``` + +Here I showed you how to use the nslookup command in Linux. Although there are other DNS lookup tools, such as dig, nslookup could be a better choice as it is a powerful tool present in almost every system. + +For more details: [Nslookup on Wikipedia](https://en.wikipedia.org/wiki/Nslookup) \ No newline at end of file diff --git a/docs/Linux-Commands/Process-Management/033-the-ps-command.md b/docs/Linux-Commands/Process-Management/033-the-ps-command.md new file mode 100755 index 0000000..d60b5cb --- /dev/null +++ b/docs/Linux-Commands/Process-Management/033-the-ps-command.md @@ -0,0 +1,54 @@ +# The `ps` command + +The `ps` command is used to identify programs and processes that are running on the system and the resources they are using. +Its frequently [pipelined]() with other commands like `grep` to search for a program/process or `less` +so that the user can analyze the output one page at a time. + +Let's say you have a program like openshot which is notorious for hogging system resources when exporting a video, and you want to close it, but the GUI has become unresponsive. + +### Example + +1. You want to find the PID of openshot and kill it. + +``` +ps aux | grep openshot +kill - +``` + +2. To Show all the running processes: + +``` +ps -A +``` + + +### Syntax + +`ps [options]` + +When run without any options, it's useless and will print: `CMD` - the executable processes/(program) running, their `PID` - process ID, `TTY` - terminal type and `Time` - How long the process has utilized the CPU or thread. + +### Common Option + +If you are going to remember only one thing from this page let it be these three letter `aux`: +`a` - which displays all processes running, including those being run by other users. +`u` - which shows the effective user of a process, i.e. the person whose file access permissions are used by the process. +`x` - which shows processes that do not have a `TTY` associated with them. + +### Additional Options: + +|**Option** |**Description** | +|:---|:---| +|`a`|Shows list all processes with a terminal (tty)| +|`-A`|Lists all processes. Identical to `-e`| +|`-a`|Shows all processes except both session leaders and processes not associated with a terminal| +|`-d`|Select all processes except session leaders| +|`--deselect`|Shows all processes except those that fulfill the specified conditions. Identical to `-N`| +|`-e`|Lists all processes. Identical to `-A`| +|`-N`|Shows all processes except those that fulfill the specified conditions. Identical to `-deselect`| +|`T`|Select all processes associated with this terminal. Identical to the `-t` option without any argument| +|`r`|Restrict the selection to only running processes| +|`--help simple`|Shows all the basic options| +|`--help all`|Shows every available options| + +Another useful command which give a realtime snapshot of the processes and the resources they are using about every ten seconds is `top`. diff --git a/docs/Linux-Commands/Process-Management/034-the-kill-command.md b/docs/Linux-Commands/Process-Management/034-the-kill-command.md new file mode 100755 index 0000000..a954564 --- /dev/null +++ b/docs/Linux-Commands/Process-Management/034-the-kill-command.md @@ -0,0 +1,89 @@ +# The `kill` command + +`kill` command in Linux (located in /bin/kill), is a built-in command which is used to terminate processes manually. The `kill` command sends a signal to a process which terminates the process. If the user doesn’t specify any signal which is to be sent along with kill command then default _TERM_ signal is sent that terminates the process. + +Signals can be specified in three ways: +- **By number (e.g. -5)** +- **With SIG prefix (e.g. -SIGkill)** +- **Without SIG prefix (e.g. -kill)** + +### Syntax + +``` +kill [OPTIONS] [PID]... +``` + +### Examples: +1. To display all the available signals you can use below command option: + +``` +kill -l +``` + +2. To show how to use a _PID_ with the _kill_ command. + +``` +$kill pid +``` + +3. To show how to send signal to processes. +``` +kill {-signal | -s signal} pid +``` + +4. Specify Signal: + +- using numbers as signals +``` +kill -9 pid +``` +- using SIG prefix in signals +``` +kill -SIGHUP pid +``` +- without SIG prefix in signals +``` +kill -HUP pid +``` + + +### Arguments: +The list of processes to be signaled can be a mixture of names and PIDs. + + pid Each pid can be expressed in one of the following ways: + + n where n is larger than 0. The process with PID n is signaled. + + 0 All processes in the current process group are signaled. + + -1 All processes with a PID larger than 1 are signaled. + + -n where n is larger than 1. All processes in process group n are signaled. + When an argument of the form '-n' is given, and it is meant to denote a + process group, either a signal must be specified first, or the argument must + be preceded by a '--' option, otherwise it will be taken as the signal to + send. + + name All processes invoked using this name will be signaled. +### Options: + -s, --signal signal + The signal to send. It may be given as a name or a number. + + -l, --list [number] + Print a list of signal names, or convert the given signal number to a name. The + signals can be found in /usr/include/linux/signal.h. + + -L, --table + Similar to -l, but it will print signal names and their corresponding numbers. + + -a, --all + Do not restrict the command-name-to-PID conversion to processes with the same UID + as the present process. + + -p, --pid + Only print the process ID (PID) of the named processes, do not send any signals. + + --verbose + Print PID(s) that will be signaled with kill along with the signal. + + diff --git a/docs/Linux-Commands/Process-Management/035-the-killall-command.md b/docs/Linux-Commands/Process-Management/035-the-killall-command.md new file mode 100755 index 0000000..ce2cbf0 --- /dev/null +++ b/docs/Linux-Commands/Process-Management/035-the-killall-command.md @@ -0,0 +1,129 @@ +# The `killall` command + +`killall` sends a signal to **all** processes running any of the specified commands. If no signal name is specified, `SIGTERM` is sent. In general, `killall` command kills all processes by knowing the name of the process. + +Signals can be specified either by name (e.g. `-HUP` or `-SIGHUP`) or by number (e.g. `-1`) or by option `-s`. + +If the command name is not a regular expression (option `-r`) and contains a slash (`/`), processes executing that particular file will be selected for killing, independent of their name. + +`killall` returns a zero return code if at least one process has been killed for each listed command, or no commands were listed and at least one process matched the `-u` and `-Z` search criteria. `killall` returns non-zero otherwise. + +A `killall` process never kills itself (but may kill other `killall` processes). + +### Examples: + +1. Kill all processes matching the name `conky` with `SIGTERM`: + +```sh +killall conky +# OR +killall -SIGTERM conky +# OR +kilall -15 conky +``` + +I was able to kill Wine ( which are Windows exe files running on Linux ) applications this way too. + +```sh +killall TQ.exe +``` + +2. List all the supported signals: + +```sh +$ killall -l +HUP INT QUIT ILL TRAP ABRT BUS FPE KILL USR1 SEGV USR2 PIPE ALRM TERM STKFLT +CHLD CONT STOP TSTP TTIN TTOU URG XCPU XFSZ VTALRM PROF WINCH POLL PWR SYS +``` + +As for the numbers. + +```sh +$ for s in $(killall -l); do echo -n "$s " && kill -l $s; done +HUP 1 +INT 2 +QUIT 3 +ILL 4 +TRAP 5 +ABRT 6 +BUS 7 +FPE 8 +KILL 9 +USR1 10 +SEGV 11 +USR2 12 +PIPE 13 +ALRM 14 +TERM 15 +STKFLT 16 +CHLD 17 +CONT 18 +STOP 19 +TSTP 20 +TTIN 21 +TTOU 22 +URG 23 +XCPU 24 +XFSZ 25 +VTALRM 26 +PROF 27 +WINCH 28 +POLL 29 +PWR 30 +SYS 31 +``` + +3. Ask before killing, to prevent unwanted kills: + +```sh +$ killall -i conky +Kill conky(1685) ? (y/N) +``` + +4. Kill all processes and wait until the processes die. + +```sh +killall -w conky +``` + +5. Kill based on time: + +```sh +# Kill all firefox younger than 2 minutes +killall -y 2m firefox + +# Kill all firefox older than 2 hours +killall -o 2h firefox +``` + +### Syntax: + +```sh +killall [OPTION]... [--] NAME... +killall -l, --list +killall -V, --version +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-e`|`--exact`|require an exact match for very long names| +|`-I`|`--ignore-case`|case insensitive process name match| +|`-g`|`--process-group`|kill process group instead of process| +|`-y`|`--younger-than`|kill processes younger than TIME| +|`-o`|`--older-than`|kill processes older than TIME| +|`-i`|`--interactive`|ask for confirmation before killing| +|`-l`|`--list`|list all known signal names| +|`-q`|`--quiet`|don't print complaints| +|`-r`|`--regexp`|interpret NAME as an extended regular expression| +|`-s`|`--signal SIGNAL`|send this signal instead of SIGTERM| +|`-u`|`--user USER`|kill only process(es) running as USER| +|`-v`|`--verbose`|report if the signal was successfully sent| +|`-w`|`--wait`|wait for processes to die| +|`-n`|`--ns PID`|match processes that belong to the same namespaces as PID +|`-Z`|`--context`|REGEXP kill only process(es) having context (must precede other arguments) + +### Related commands + +[kill](/ebook/en/content/034-the-kill-command.md), `pidof` diff --git a/docs/Linux-Commands/Process-Management/093-the-nohup-command.md b/docs/Linux-Commands/Process-Management/093-the-nohup-command.md new file mode 100755 index 0000000..984d62e --- /dev/null +++ b/docs/Linux-Commands/Process-Management/093-the-nohup-command.md @@ -0,0 +1,18 @@ +# The `nohup` command + +When a shell exits (maybe while logging out of an SSH session), the HUP ('hang up') signal is send to all of its child processes, causing them to terminate. If you require a long-running process to continue after exiting shell, you'll need the `nohup` command. Prefixing any command with `nohup` causes the command to become _immune_ to HUP signals. Additionally, STDIN is being ignored and all output gets redirected to local file `./nohup.out`. + +### Examples: + +1. Applying nohup to a long-running debian upgrade: + +``` +nohup apt-get -y upgrade +``` + +### Syntax: + +``` +nohup COMMAND [ARG]... +nohup OPTION +``` diff --git a/docs/Linux-Commands/System/013-the-uname-command.md b/docs/Linux-Commands/System/013-the-uname-command.md new file mode 100755 index 0000000..3cb1529 --- /dev/null +++ b/docs/Linux-Commands/System/013-the-uname-command.md @@ -0,0 +1,31 @@ +# The `uname` command +The `uname` command lets you print out system information and defaults to outputting the kernel name. + +## Syntax: +```bash +$ uname [OPTION] +``` + +## Examples +1. Print out all system information. +```bash +$ uname -a +``` + +2. Print out the kernel version. +```bash +$ uname -v +``` + +## Options +|**Short Flag**|**Long Flag**|**Description**| +|:-|:-|:-| +|`-a`|`--all`|Print all information, except omit processor and hardware platform if unknown.| +|`-s`|`--kernel-name`|Print the kernel name.| +|`-n`|`--nodename`|Print the network node hostname.| +|`-r`|`--kernel-release`|Print the kernel release.| +|`-v`|`--kernel-version`|Print the kernel version.| +|`-m`|`--machine`|Print the machine hardware name.| +|`-p`|`--processor`|Print the processor type (non-portable).| +|`-i`|`--hardware-platform`|Print the hardware platform (non-portable).| +|`-o`|`--operating-system`|Print the operating system.| diff --git a/docs/Linux-Commands/System/024-the-man-command.md b/docs/Linux-Commands/System/024-the-man-command.md new file mode 100755 index 0000000..28cfaea --- /dev/null +++ b/docs/Linux-Commands/System/024-the-man-command.md @@ -0,0 +1,39 @@ +# The `man` command + +The `man` command is used to display the manual of any command that we can run on the terminal. +It provides information like: DESCRIPTION, OPTIONS, AUTHORS and more. + +### Examples: + +1. Man page for printf: + +``` +man printf +``` + +2. Man page section 2 for intro: + +``` +man 2 intro +``` +3. Viewing the Manual for a Local File (using the -l flag): + +``` +man -l [LOCAL-FILE] +``` + +### Syntax: + +``` +man [SECTION-NUM] [COMMAND NAME] +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-f`|
-
|Return the sections of an command| +|`-a`|
-
|Display all the manual pages of an command| +|`-k`|
-
|Searches the given command with RegEx in all man pages| +|`-w`|
-
|Returns the location of a given command man page| +|`-I`|
-
|Searches the command manual case sensitive| diff --git a/docs/Linux-Commands/System/036-the-env-command.md b/docs/Linux-Commands/System/036-the-env-command.md new file mode 100755 index 0000000..5cb0a8e --- /dev/null +++ b/docs/Linux-Commands/System/036-the-env-command.md @@ -0,0 +1,41 @@ +# The `env` command + +The `env` command in Linux/Unix is used to either print a list of the current environment variables or to run a program in a custom environment without changing the current one. + +## Syntax + +```bash +env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...] +``` + +## Usage + +1. Print out the set of current environment variables + ```bash + env + ``` +2. Run a command with an empty environment + ```bash + env -i command_name + ``` +3. Remove variable from the environment + ```bash + env -u variable_name + ``` +4. End each output with NULL + ```bash + env -0 + ``` + +## Full List of Options + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-i`|`--ignore-environment`|Start with an empty environment| +|`-0`|`--null`|End each output line with NUL, not newline| +|`-u`|`--unset=NAME `|Remove variable from the environment| +|`-C`|`--chdir=DIR`|Change working directory to DIR| +|`-S`|`--split-string=S`|Process and split S into separate arguments. It's used to pass multiple arguments on shebang lines| +|`-v`|`--debug`|Print verbose information for each processing step| +|-|`--help`|Print a help message| +|-|`--version`|Print the version information| \ No newline at end of file diff --git a/docs/Linux-Commands/System/038-the-hostname-command.md b/docs/Linux-Commands/System/038-the-hostname-command.md new file mode 100755 index 0000000..e2d1b20 --- /dev/null +++ b/docs/Linux-Commands/System/038-the-hostname-command.md @@ -0,0 +1,26 @@ +# The `hostname` command + +`hostname` is used to display the system's DNS name, and to display or set its hostname or NIS domain name. +### Syntax: + +``` +hostname [-a|--alias] [-d|--domain] [-f|--fqdn|--long] [-A|--all-fqdns] [-i|--ip-address] [-I|--all-ip-addresses] [-s|--short] [-y|--yp|--nis] +``` + +### Examples: + +1. ``` hostname -a, hostname --alias ``` + Display the alias name of the host (if used). This option is deprecated and should not be used anymore. + +2. ```hostname -s, hostname --short``` + Display the short host name. This is the host name cut at the first dot. + +3. ```hostname -V, hostname --version``` + Print version information on standard output and exit successfully. + + +### Help Command +Run below command to view the complete guide to `hostname` command. +``` +man hostname +``` \ No newline at end of file diff --git a/docs/Linux-Commands/System/044-the-su-command.md b/docs/Linux-Commands/System/044-the-su-command.md new file mode 100755 index 0000000..9778671 --- /dev/null +++ b/docs/Linux-Commands/System/044-the-su-command.md @@ -0,0 +1,39 @@ +# The `su` command + +In linux, `su` allows you to run commands with a substitute user and group ID. + +When called without arguments, `su` defaults to running an interactive shell as root. + +## Example : + +```bash +$ su +``` + +In case that you wanted to switch to a user called `devdojo`, you could do that by running the following command: + +``` +$ su devdojo +``` + +## The syntax of the `su` command is : + +```bash +$ su [options] [-] [[...]] + +``` + +## Options : + +```bash +-m, -p --> do not reset environment variables +-w --> do not reset specified variables +-g --> specify the primary group +-G --> specify a supplemental group +-l --> make the shell a login shell +-f --> pass -f to the shell (for csh or tcsh) +-s --> run if /etc/shell allows it +-p --> create a new pseudo terminal +-h --> display this help +-v --> display version +``` diff --git a/docs/Linux-Commands/System/051-the-sudo-command.md b/docs/Linux-Commands/System/051-the-sudo-command.md new file mode 100755 index 0000000..18a7b34 --- /dev/null +++ b/docs/Linux-Commands/System/051-the-sudo-command.md @@ -0,0 +1,52 @@ +# The `sudo` command + +The `sudo` ("substitute user do" or "super user do") command allows a user with proper permissions to execute a command as another user, such as the superuser. + +This is the equivalent of "run as administrator" option in Windows. The `sudo` command allows you to elevate your current user account to have root privileges. Also, the root privilege in `sudo` is only valid for a temporary amount of time. Once that time expires, you have to enter your password again to regain root privilege. + +> WARNING: Be very careful when using the `sudo` command. You can cause irreversible and catastrophic changes while acting as root! + +### Syntax: + +``` +sudo [-OPTION] command +``` + +### Additional Flags and their Functionalities: + +|**Flag** |**Description** | +|:---|:---| +|`-V`|The -V (version) option causes sudo to print the version number and exit. If the invoking user is already root, the -V option prints out a list of the defaults sudo was compiled with and the machine's local network addresses| +|`-l`|The -l (list) option prints out the commands allowed (and forbidden) the user on the current host.| +|`-L`|The -L (list defaults) option lists out the parameters set in a Defaults line with a short description for each. This option is useful in conjunction with grep.| +|`-h`|The -h (help) option causes sudo to print a usage message and exit.| +|`-v`|If given the `-v` (validate) option, `sudo` updates the user's timestamp, prompting for the user's password if necessary. This extends the sudo timeout for another 5 minutes (or whatever the timeout is set to in sudoers) but does not run a command.| +|`-K`|The -K (sure kill) option to sudo removes the user's timestamp entirely. Likewise, this option does not require a password.| +|`-u`|The -u (user) option causes sudo to run the specified command as a user other than root. To specify a uid instead of a username, use #uid.| +|`-s`|The -s (shell) option runs the shell specified by the SHELL environment variable if it's set or the shell as specified in the file passwd.| +|`--`|The -- flag indicates that sudo should stop processing command line arguments. It is most useful in conjunction with the -s flag.| + +## Examples +This command switches your command prompt to the BASH shell as a root user: + +``` +sudo bash +``` +Your command line should change to: + +``` +root@hostname:/home/[username] +``` + +Adding a string of text to a file is often used to add the name of a software repository to the sources file, without opening the file for editing. Use the following syntax with echo, sudo and tee command: + + +``` +echo ‘string-of-text’ | sudo tee -a [path_to_file] +``` + +Example: + +```` +echo "deb http://nginx.org/packages/debian `lsb_release -cs` nginx" \ | sudo tee /etc/apt/sources.list.d/nginx.list +```` diff --git a/docs/Linux-Commands/System/052-the-apt-command.md b/docs/Linux-Commands/System/052-the-apt-command.md new file mode 100755 index 0000000..8d629a8 --- /dev/null +++ b/docs/Linux-Commands/System/052-the-apt-command.md @@ -0,0 +1,80 @@ +# The `apt` command + +`apt` (Advantage package system) command is used for interacting with `dpkg` (packaging system used by debian). There is already the `dpkg` command to manage `.deb` packages. But `apt` is a more user-friendly and efficient way. + +In simple terms `apt` is a command used for installing, deleting and performing other operations on debian based Linux. + +You will be using the `apt` command mostly with `sudo` privileges. + +### Installing packages: +`install` followed by `package_name` is used with `apt` to install a new package. +##### Syntax: +``` +sudo apt install package_name +``` +##### Example: +``` +sudo apt install g++ +``` +This command will install g++ on your system. + + +### Removing packages: +`remove` followed by `package_name` is used with `apt` to remove a specific package. +##### Syntax: +``` +sudo apt remove package_name +``` +##### Example: +``` +sudo apt remove g++ +``` +This command will remove g++ from your system. + + +### Searching for a package: +`search` followed by the `package_name` used with apt to search a package across all repositories. +##### Syntax: +``` +apt search package_name +``` +note: sudo not required +##### Example: +``` +apt search g++ +``` + +### Removing unused packages: +Whenever a new package that depends on other packages is installed on the system, the package dependencies will be installed too. When the package is removed, the dependencies will stay on the system. This leftover packages are no longer used by anything else and can be removed. + +##### Syntax: +``` +sudo apt autoremove +``` +This command will remove all unused from your system. + + +### Updating package index: +`apt` package index is nothing but a database that stores records of available packages that are enabled on your system. + +##### Syntax: +``` +sudo apt update +``` +This command will update the package index on your system. + + +### Upgrading packages: +If you want to install the latest updates for your installed packages you may want to run this command. +##### Syntax: +``` +sudo apt upgrade +``` +The command doesn't upgrade any packages that require removal of installed packages. + +If you want to upgrade a single package, pass the package name: +##### Syntax: +``` +sudo apt upgrade package_name +``` +This command will upgrade your packages to the latest version. diff --git a/docs/Linux-Commands/System/053-the-yum-command.md b/docs/Linux-Commands/System/053-the-yum-command.md new file mode 100755 index 0000000..2226d96 --- /dev/null +++ b/docs/Linux-Commands/System/053-the-yum-command.md @@ -0,0 +1,61 @@ +# The `yum` command + +The `yum`command is the primary package management tool for installing, updating, removing, and managing software packages in Red Hat Enterprise Linux. It is an acronym for _`Yellow Dog Updater, Modified`_. + +`yum` performs dependency resolution when installing, updating, and removing software packages. It can manage packages from installed repositories in the system or from .rpm packages. + +### Syntax: + +```[linux] +yum -option command +``` + +### Examples: + +1. To see an overview of what happened in past transactions: + +```[linux] +yum history +``` + +2. To undo a previous transaction: + +```[linux] +yum history undo +``` + +3. To install firefox package with 'yes' as a response to all confirmations + +```[linux] +yum -y install firefox +``` + +4. To update the mysql package it to the latest stable version + +```[linux] +yum update mysql +``` + +### Commonly used commands along with yum: + +| **Command** | **Description** | +| :------------- | :------------------------------------------------ | +| `install` | Installs the specified packages | +| `remove` | Removes the specified packages | +| `search` | Searches package metadata for keywords | +| `info` | Lists the description | +| `update` | Updates each package to the latest version | +| `repolist` | Lists repositories | +| `history` | Displays what has happened in past transactions | +| `groupinstall` | To install a particular package group | +| `clean` | To clean all cached files from enabled repository | + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :---------------- | :-------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------- | +| `-C` | `--cacheonly` | Runs entirely from system cache, doesn’t update the cache and use it even in case it is expired. | +|
-
| `--security` | Includes packages that provide a fix for a security issue. Applicable for the upgrade command. | +| `-y` | `--assumeyes` | Automatically answer yes for all questions. | +|
-
| `--skip-broken` | Resolves depsolve problems by removing packages that are causing problems from the transaction. It is an alias for the strict configuration option with value False. | +| `-v` | `--verbose` | Verbose operation, show debug messages. | diff --git a/docs/Linux-Commands/System/056-the-shutdown-command.md b/docs/Linux-Commands/System/056-the-shutdown-command.md new file mode 100755 index 0000000..cd5e11c --- /dev/null +++ b/docs/Linux-Commands/System/056-the-shutdown-command.md @@ -0,0 +1,39 @@ +# The `shutdown` command + +The `shutdown` command lets you bring your system down in a secure way. When `shutdown` is executed the system will notify all logged-in users and disallow further logins. +You have the option to shut down your system immediately or after a specific time. + +Only users with root (or sudo) privileges can use the `shutdown` command. + +### Examples: + +1. Shut down your system immediately: + +``` +sudo shutdown now +``` + +2. Shut down your system after 10 minutes: + +``` +sudo shutdown +10 +``` + +3. Shut down your system with a message after 5 minutes: + +``` +sudo shutdown +5 "System will shutdown in 5 minutes" +``` + +### Syntax: + +``` +shutdown [OPTIONS] [TIME] [MESSAGE] +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-r`|
-
|Reboot the system| +|`-c`|
-
|Cancel an scheduled shut down| diff --git a/docs/Linux-Commands/System/058-the-reboot-command.md b/docs/Linux-Commands/System/058-the-reboot-command.md new file mode 100755 index 0000000..20fc3dc --- /dev/null +++ b/docs/Linux-Commands/System/058-the-reboot-command.md @@ -0,0 +1,56 @@ +# The `reboot` Command + +The `reboot` command is used to restart a linux system. However, it requires elevated permission using the [sudo](https://github.com/bobbyiliev/101-linux-commands-ebook/blob/main/ebook/en/content/051-the-sudo-command.md) command. Necessity to use this command usually arises after significant system or network updates have been made to the system. + +## Syntax +``` +reboot [OPTIONS...] +``` + +### Options +- **–help** : This option prints a short help text and exit. +- **-halt** : This command will stop the machine. +- **-w**, **–wtmp-only** : This option only writes wtmp shutdown entry, it do not actually halt, power-off, reboot. + +### Examples +1. Basic Usage. Mainly used to restart without any further details +``` +$ sudo reboot +``` +However, alternatively the shutdown command with the `-r` option +``` +$ sudo shutdown -r now +``` + +**Note** that the usage of the reboot, halt and power off is almost similar in syntax and effect. Run each of these commands with –help to see the details. + +2. The `reboot` command has limited usage, and the `shutdown` command is being used instead of reboot command to fulfill much more advance reboot and shutdown requirements. One of those situations is a scheduled restart. Syntax is as follows +``` +$ sudo shutdown –r [TIME] [MESSAGE] +``` +Here the TIME has various formats. The simplest one is `now`, already been listed in the previous section, and tells the system to restart immediately. Other valid formats we have are +m, where m is the number of minutes we need to wait until restart and HH:MM which specifies the TIME in a 24hr clock. + +**Example to reboot the system in 2 minutes** +``` +$ sudo shutdown –r +2 +``` + +**Example of a scheduled restart at 03:00 A.M** +``` +$ sudo shutdown –r 03:00 +``` +3. Cancelling a Reboot. Usually happens in case one wants to cancel a scheduled restart + +**Syntax** +``` +$ sudo shutdown –c [MESSAGE] +``` +**Usage** +``` +$sudo shutdown -c "Scheduled reboot cancelled because the chicken crossed the road" +``` + +4. Checking your reboot logs +``` +$ last reboot +``` diff --git a/docs/Linux-Commands/System/065-the-hostnamectl-command.md b/docs/Linux-Commands/System/065-the-hostnamectl-command.md new file mode 100755 index 0000000..831a509 --- /dev/null +++ b/docs/Linux-Commands/System/065-the-hostnamectl-command.md @@ -0,0 +1,44 @@ +# The `hostnamectl` command + +The `hostnamectl` command provides a proper API used to control Linux system hostname and change its related settings. The command also helps to change the hostname without actually locating and editing the `/etc/hostname` file on a given system. + +## Syntax +``` +$ hostnamectl [OPTIONS...] COMMAND ... +``` +where **COMMAND** can be any of the following + +**status**: Used to check the current hostname settings + +**set-hostname NAME**: Used to set system hostname + +**set-icon-name NAME**: Used to set icon name for host + + + +## Example + +1. Basic usage to view the current hostnames +``` +$ hostnamectl +``` +or +``` +$ hostnamectl status +``` + +2. To change the static host name to _myhostname_. It may or may not require root access +``` +$ hostnamectl set-hostname myhostname --static +``` + +3. To set or change a transient hostname +``` +$ hostnamectl set-hostname myotherhostname --transient +``` + +4. To set the pretty hostname. The name that is to be set needs to be in the double quote(” “). +``` +$ hostname set-hostname "prettyname" --pretty +``` + diff --git a/docs/Linux-Commands/System/091-the-crontab-command.md b/docs/Linux-Commands/System/091-the-crontab-command.md new file mode 100755 index 0000000..350d11f --- /dev/null +++ b/docs/Linux-Commands/System/091-the-crontab-command.md @@ -0,0 +1,45 @@ +# The `crontab` command + +`crontab` is used to maintain crontab files for individual users (Vixie Cron) + + +crontab is the program used to install, uninstall or list the tables used to drive the cron(8) daemon in Vixie Cron. Each user can have their own crontab, and though these are files in `/var/spool/cron/crontabs`, they are not intended to be edited directly. + +### Syntax: + +``` +crontab [ -u user ] file +crontab [ -u user ] [ -i ] { -e | -l | -r } +``` + +### Examples: + +1. The -l option causes the current crontab to be displayed on standard output. + +``` +crontab -l +``` + +2. The -r option causes the current crontab to be removed. + +``` +crontab -r +``` + +3. The -e option is used to edit the current crontab using the editor specified by the VISUAL or EDITOR environment variables. After you exit from the editor, the modified crontab will be installed automatically. If neither of the environment variables is defined, then the default editor /usr/bin/editor is used. + +``` +crontab -e +``` + +4. You can specify the user you want to edit the crontab for. Every user has its own crontab. Assume you have a `www-data` user, which is in fact the user Apache is default running as. If you want to edit the crontab for this user you can run the following command + +``` +crontab -u www-data -e +``` + +### Help Command +Run below command to view the complete guide to `crontab` command. +``` +man crontab +``` \ No newline at end of file diff --git a/docs/Linux-Commands/System/096-the-whereis-command.md b/docs/Linux-Commands/System/096-the-whereis-command.md new file mode 100755 index 0000000..5d349f7 --- /dev/null +++ b/docs/Linux-Commands/System/096-the-whereis-command.md @@ -0,0 +1,29 @@ +# The `whereis` command + +The `whereis` command is used to find the location of source/binary file of a command and manuals sections for a specified file in Linux system. If we compare `whereis` command with find command they will appear similar to each other as both can be used for the same purposes but `whereis` command produces the result more accurately by consuming less time comparatively. + +#### Points to be kept on mind while using the whereis command: + +Since the `whereis` command uses chdir(change directory 2V) to give you the result in the fastest possible way, the pathnames given with the -M, -S, or -B must be full and well-defined i.e. they must begin with a `/` and should be a valid path that exist in the system’s directories, else it exits without any valid result. +`whereis` command has a hard-coded(code which is not dynamic and changes with specification) path, so you may not always find what you’re looking for. + +### Syntax + +``` +whereis [options] [filename] +``` + +### Options + +-b : This option is used when we only want to search for binaries. +-m : This option is used when we only want to search for manual sections. +-s : This option is used when we only want to search for source files. +-u: This option search for unusual entries. A source file or a binary file is said to be unusual if it does not have any existence in system as per [-bmsu] described along with “–u”. Thus `whereis -m -u *‘ asks for those files in the current directory which have unsual entries. + +-B : This option is used to change or otherwise limit the places where whereis searches for binaries. +-M : This option is used to change or otherwise limit the places where whereis searches for manual sections. +-S : This option is used to change or otherwise limit the places where whereis searches for source files. + +-f : This option simply terminate the last directory list and signals the start of file names. This must be used when any of the -B, -M, or -S options are used. +-V: Displays version information and exit. +-h: Displays the help and exit. \ No newline at end of file diff --git a/docs/Linux-Commands/System/105-the-cmatrix-command.md b/docs/Linux-Commands/System/105-the-cmatrix-command.md new file mode 100755 index 0000000..78b44fd --- /dev/null +++ b/docs/Linux-Commands/System/105-the-cmatrix-command.md @@ -0,0 +1,29 @@ +# The `cmatrix` command + +This command doesn't come by default in Linux. It has to be installed, and as seen in chapter [052](/ebook/en/content/052-the-apt-command.md) we need to run the following command: + +``` +sudo apt-get install cmatrix +``` + +And after everything is installed, you have become a 'legit hacker'. In order to use this command, just type in `cmatrix` and press enter: + +``` +cmatrix +``` + +And this is what you should see: + +![The Matrix](https://imgur.com/h5ZKcKQ.png) + +As you can see you have access to the matrix now. Well, not really. + +What this actually is just a fun little command to goof around with. There are actually a few options you can use. For examle you can change the text colour. You can choose from **green, red, blue, white, yellow, cyan, magenta and black**. + +``` +cmatrix -C red +``` + +![Red Matrix](https://imgur.com/PwMXSVx.png) + +And the falling characters will be red. This command isn't really something that will help you with your job or anything, but it is fun to know that you can have some fun in Linux. diff --git a/docs/Linux-Commands/System/115-the-date-command.md b/docs/Linux-Commands/System/115-the-date-command.md new file mode 100755 index 0000000..15dd144 --- /dev/null +++ b/docs/Linux-Commands/System/115-the-date-command.md @@ -0,0 +1,114 @@ +# The `date` command + +The `date` command is used to print the system current date and time. + +`date` command is also used to set the date and time of the system, but you need to be the super-user *(root)* to do it. + +### Examples: + +1. To show the current date and time: + +``` +date +``` + +2. You can use -u option to show the date and time in UTC *(Coordinated Universal Time)* time zone + +``` +date -u +``` + +1. To display any given date string in formatted date: + +``` +date --date="2/02/2010" +date --date="2 years ago" +``` + +### Syntax: + +``` +date [OPTION]... [+FORMAT] +date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]] +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-d`|`--date=STRING`|convert the provided string into formatted date| +|`-f`|`--file=DATEFILE`|like `--date` but for files| +|`-I[FMT]`|`--iso-8601[=FMT]`|Display date and time in ISO 8601 format| +|`-r`|`--reference=FILE`|Display the last modification time of FILE| +|`-s`|`--set=STRING`|sets the time to the one described by STRING| +|`-u`|`--universal`|show the date and time in UTC *(Coordinated Universal Time)* time zone| +|`-R`|`--rfc-email`|Display date and time in ISO 8601 format Example: (Fri, 22 Oct 2021 05:18:42 +0200)| +|
-
|`rfc-3339=FMT`|Display date and time in RFC 3339 format| +|
-
|`--debug`|Usually used with `--date` to annotate the parsed date and warn about questionable usage to stderr| + +### Control The output: + +You can use Format specifiers to control the output date and time. + +### Examples: +|**Command** |**Output** | +|:---|:---| +|`$ date "+%D"`|`10/22/21`| +|`$ date "+%D %T"`|`10/22/21 05:33:51`| +|`$ date "+%A %B %d %T %y"`|`Friday October 22 05:34:47 21`| + +### Syntax: + +``` +date "+%[format-options ...]" +``` + +### List of Format specifiers to control the output: + +|**Specifiers** |**Description** | +|:---|:---| +|`%a`|abbreviated weekday name *(e.g., Sun)*| +|`%A`|full weekday name *(e.g., Sunday)*| +|`%b`|abbreviated month name *(e.g., Jan)*| +|`%B`|full month name *(e.g., January)*| +|`%c`|date and time *(e.g., Thu Mar 3 23:05:25 2005)*| +|`%C`|century; like %Y, except omit last two digits (e.g., 20)| +|`%d`|day of month (e.g., 01)| +|`%D`|date; same as %m/%d/%y| +|`%e`|day of month, space padded; same as %_d| +|`%F`|full date; same as %Y-%m-%d| +|`%g`|last two digits of year of ISO week number (see %G)| +|`%G`|year of ISO week number (see %V); normally useful only with %V| +|`%h`|same as %b| +|`%H`|hour (00..23)| +|`%I`|hour (01..12)| +|`%j`|day of year (001..366)| +|`%k`|hour, space padded ( 0..23); same as %_H| +|`%l`|hour, space padded ( 1..12); same as %_I| +|`%m`|month (01..12)| +|`%M`|minute (00..59)| +|`%n`|a newline| +|`%N`|nanoseconds (000000000..999999999)| +|`%p`|locale's equivalent of either AM or PM; blank if not known| +|`%P`|like %p, but lower case| +|`%q`|quarter of year (1..4)| +|`%r`|locale's 12-hour clock time (e.g., 11:11:04 PM)| +|`%R`|24-hour hour and minute; same as %H:%M| +|`%s`|seconds since 1970-01-01 00:00:00 UTC| +|`%S`|second (00..60)| +|`%t`|a tab| +|`%T`|time; same as %H:%M:%S| +|`%u`|day of week (1..7); 1 is Monday| +|`%U`|week number of year, with Sunday as first day of week (00..53)| +|`%V`|ISO week number, with Monday as first day of week (01..53)| +|`%w`|day of week (0..6); 0 is Sunday| +|`%W`|week number of year, with Monday as first day of week (00..53)| +|`%x`|locale's date representation (e.g., 12/31/99)| +|`%X`|locale's time representation (e.g., 23:13:48)| +|`%y`|last two digits of year (00..99)| +|`%Y`|year| +|`%z`|+hhmm numeric time zone (e.g., -0400)| +|`%:z`|+hh:mm numeric time zone (e.g., -04:00)| +|`%::z`|+hh:mm:ss numeric time zone (e.g., -04:00:00)| +|`%:::z`|numeric time zone with : to necessary precision (e.g., -04, +05:30)| +|`%Z`|alphabetic time zone abbreviation (e.g., EDT)| diff --git a/docs/Linux-Commands/Terminal-Experience/002-the-cd-command.md b/docs/Linux-Commands/Terminal-Experience/002-the-cd-command.md new file mode 100755 index 0000000..a19e2c3 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/002-the-cd-command.md @@ -0,0 +1,56 @@ +# The `cd` command + +The `cd` command is used to change the current working directory *(i.e., in which the current user is working)*. The "cd" stands for "**c**hange **d**irectory" and it is one of the most frequently used commands in the Linux terminal. + +The `cd` command is often combined with the `ls` command (see chapter 1) when navigating through a system, however, you can also press the `TAB` key two times to list the contents of the new directory you just changed to. + +### Examples of uses: + +1. Change the current working directory: +``` +cd +``` + +2. Change the current working directory to the home directory: +``` +cd ~ +``` +OR +``` +cd +``` + +3. Change to the previous directory: +``` +cd - +``` +This will also echo the absolute path of the previous directory. + +4. Change the current working directory to the system's root directory: +``` +cd / +``` + +### 💡 Quick Tips + +Adding a `..` as a directory will allow you to move "up" from a folder: +``` +cd .. +``` +This can also be done multiple times! For example, to move up three folders: +``` +cd ../../../ +``` + +### Syntax: + +``` +cd [OPTIONS] directory +``` + +### Additional Flags and Their Functionalities + +|**Short flag** |**Long flag** |**Description** | +|:---|:---|:---| +|`-L`|
-
|Follow symbolic links. By default,`cd` behaves as if the `-L` option is specified.| +|`-P`|
-
|Don’t follow symbolic links.| diff --git a/docs/Linux-Commands/Terminal-Experience/004-the-head-command.md b/docs/Linux-Commands/Terminal-Experience/004-the-head-command.md new file mode 100755 index 0000000..9fc3c1c --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/004-the-head-command.md @@ -0,0 +1,41 @@ +# The `head` command + +The `head` command prints the first ten lines of a file. + +Example: +``` +head filename.txt +``` + +Syntax: +``` +head [OPTION] [FILENAME] +``` + +### Get a specific number of lines: + +Use the `-n` option with a number (should be an integer) of lines to display. + +Example: +``` +head -n 10 foo.txt +``` + +This command will display the first ten lines of the file `foo.txt`. + +Syntax: +``` +head -n foo.txt +``` +### Additional Flags and their Functionalities + + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-c`|`--bytes=[-]NUM`|Print the first NUM bytes of each file;
with the leading '-',
print all but the last NUM bytes of each file| +|`-n`|`--lines=[-]NUM`|Print the first NUM lines instead of the first 10;
with the leading '-',
print all but the last NUM lines of each file| +|`-q`|`--quiet, --silent`|Never print headers giving file names| +|`-v`|`--verbose`|Always print headers giving file names| +|`-z`|`--zero-terminated`|Line delimiter is NUL, not newline| +|` `|`--help`| Display this help and exit| +|` `|`--version`|Output version information and exit| \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/005-the-tail-command.md b/docs/Linux-Commands/Terminal-Experience/005-the-tail-command.md new file mode 100755 index 0000000..6ae2c7f --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/005-the-tail-command.md @@ -0,0 +1,56 @@ +# The `tail` command + +The `tail` command prints the last ten lines of a file. + +Example: +``` +tail filename.txt +``` + +Syntax: +``` +tail [OPTION] [FILENAME] +``` + +### Get a specific number of lines with `tail`: + +Use the `-n` option with a number(should be an integer) of lines to display. + +Example: +``` +tail -n 10 foo.txt +``` + +This command will display the last ten lines of the file `foo.txt`. + +### Refresh the output on any new entry in a file + +It is possible to let tail output any new line added to the file you are looking into. So, if a new line is written to the file, it will immediately be shown in your output. This can be done using the `--follow` or `-f` option. This is especially useful for monitoring log files. + +Example: +``` +tail -f foo.txt +``` + +Syntax: +``` +tail -n foo.txt +``` + +### Additional Flags and their Functionalities + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-c`|`--bytes=[+]NUM`|Output the last NUM bytes;
or use -c +NUM to
output starting with byte NUM of each file| +|`-f`|--follow[={name|descriptor}]|Output appended data as the file grows;
an absent option argument means 'descriptor'| +|`-F`||Same as --follow=name --retry| +|`-n`|`--lines=[+]NUM`|Output the last NUM lines, instead of the last 10;
or use -n +NUM to output starting with line NUM| +||`--max-unchanged-stats=N`|with --follow=name, reopen a FILE which has not
changed size after N (default 5) iterations
to see if it has been unlinked or rename
(this is the usual case of rotated log files);
with inotify, this option is rarely useful| +||`--pid=PID`|with -f, terminate after process ID, PID dies| +|`-q`|`--quiet, --silent`|Never output headers giving file names| +|``|`--retry`|keep trying to open a file if it is inaccessible| +|`-s`|`--sleep-interval=N`|With -f, sleep for approximately N seconds
(default 1.0) between iterations;
with inotify and --pid=P, check process P at
least once every N seconds| +|`-v`|`--verbose`|Always output headers giving file names| +|`-z`|`--zero-terminated`|Line delimiter is NUL, not newline| +||`--help`|Display this help and exit| +||`--version`|Output version information and exit| diff --git a/docs/Linux-Commands/Terminal-Experience/006-the-pwd-command.md b/docs/Linux-Commands/Terminal-Experience/006-the-pwd-command.md new file mode 100755 index 0000000..13bbf6f --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/006-the-pwd-command.md @@ -0,0 +1,40 @@ +# The `pwd` command + +The `pwd` stands for Print Working Directory. It prints the path of the current working directory, starting from the root. + +Example: +``` +pwd +``` + +The output would be your current directory: + +``` +/home/your_user/some_directory +``` + +Syntax: +``` +pwd [OPTION] +``` + +Tip: +You can also check this by printing out the `$PWD` variable: + +``` +echo $PWD +``` + +The output would be the same as of the `pwd` command. + +### Options: + + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +| `-L` | `--logical` | If the environment variable $PWD contains an absolute name of the current directory with no "." or ".." components, then output those contents, even if they contain symbolic links. Otherwise, fall back to default (-P) behavior. | +| `-P`| `--physical` | Print a fully resolved name for the current directory, where all components of the name are actual directory names, and not symbolic links. | +| ` ` | `--help`| Display a help message, and exit. | +| ` ` | `--version`| Display version information, and exit. | + +By default, `pwd' behaves as if `-L' were specified. diff --git a/docs/Linux-Commands/Terminal-Experience/019-the-top-htop-command.md b/docs/Linux-Commands/Terminal-Experience/019-the-top-htop-command.md new file mode 100755 index 0000000..e5f94e4 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/019-the-top-htop-command.md @@ -0,0 +1,92 @@ +# The `top/htop` command + +`top` is the default command-line utility that comes pre-installed on Linux distributions and Unix-like operating systems. It is used for displaying information about the system and its top CPU-consuming processes as well as RAM usage. + +`htop` is interactive process-viewer and process-manager for Linux and Unix-like operating system based on ncurses. If you take top and put it on steroids, you get htop. + +## Comparison between top and htop: + +|**Feature** |**top** |**htop** | +|:---|:---|:---| +|Type|Interactive system-monitor, process-viewer and process-manager|Interactive system-monitor, process-viewer and process-manager| +|Operating System|Linux distributions, macOS |Linux distributions, macOS | +|Installation|Built-in and is always there. Also has more adoption due to this fact.|Doesn't come preinstalled on most Linux distros. Manual installation is needed| +|User Interface|Basic text only|Colorful and nicer text-graphics interface| +|Scrolling Support|No|Yes, supports horizontal and vertical scrolling| +|Mouse Support|No|Yes| +|Process utilization|Displays processes but not in tree format|Yes, including user and kernel threads| +|Scrolling Support|No|Yes, supports horizontal and vertical scrolling| +|Mouse Support|No|Yes| +|Process utilization|Displays processes but not in tree format|Yes, including user and kernel threads| +|Network Utilization|No|No| +|Disk Utilization|No|No| +|Comments|Has a learning curve for some advanced options like searching, sending messages to processes, etc. It is good to have some knowledge of top because it is the default process viewer on many systems.|Easier to use and supports vi like searching with `/`. Sending messages to processes (kill, renice) is easier and doesn't require typing in the process number like top.| + +## Examples: + +### `top` + +1. To display dynamic real-time information about running processes: + +``` +top +``` + +2. Sorting processes by internal memory size (default order - process ID): + +``` +top -o mem +``` + +3. Sorting processes first by CPU, then by running time: + +``` +top -o cpu -O time +``` + +4. Display only processes owned by given user: + +``` +top -user {user_name} +``` + +### `htop` + +1. Display dynamic real-time information about running processes. An enhanced version of `top`. + +``` +htop +``` + +2. displaying processes owned by a specific user: + +``` +htop --user {user_name} +``` + +3. Sort processes by a specified `sort_item` (use `htop --sort help` for available options): + +``` +htop --sort {sort_item} +``` + +## Syntax: + +``` +top [OPTIONS] +``` + +``` +htop [OPTIONS] +``` + + +## Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-a`|
-
|Sort by memory usage.| +|`-b`|
-
|Batch mode operation. Starts top in 'Batch mode', which could be useful for sending output from top to other programs or to a file. In this mode, top will not accept input and runs until the iterations limit you've set with the '-n' command-line option or until killed.| +|`-h`|
-
|`top --user {user_name}` Only display processes owned by user.| +|`-U`|
-user
|Help.| +|`-u`|
-
|This is an alias equivalent to: -o cpu -O time.| \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/021-the-echo-command.md b/docs/Linux-Commands/Terminal-Experience/021-the-echo-command.md new file mode 100755 index 0000000..d34a5ae --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/021-the-echo-command.md @@ -0,0 +1,45 @@ +# The `echo` command + +The `echo` command lets you display the line of text/string that is passed as an argument + +### Examples: + +1. To Show the line of text or string passed as an argument: + +``` +echo Hello There +``` +2. To show all files/folders similar to the `ls` command: +``` +echo * +``` +3. To save text to a file named foo.bar: +``` +echo "Hello There" > foo.bar +``` +4. To append text to a file named foo.bar: +``` +echo "Hello There" >> foo.bar +``` +### Syntax: + +``` +echo [option] [string] +``` + +#### It is usually used in shell scripts and batch files to output status text to the screen or a file.The `-e` used with it enables the interpretation of backslash escapes + + +### Additional Options and their Functionalities: + + +|**Option** |**Description** | +|:---|:---| +|`\b`|removes all the spaces in between the text| +|`\c`|suppress trailing new line with backspace interpretor ‘-e‘ to continue without emitting new line.| +|`\n`|creates new line from where it is used| +|`\t`|creates horizontal tab spaces| +|`\r`|carriage returns with backspace interpretor ‘-e‘ to have specified carriage return in output| +|`\v`|creates vertical tab spaces| +|`\a`|alert returns with a backspace interpretor ‘-e‘ to have sound alert| +|`-n`|omits echoing trailing newline .| diff --git a/docs/Linux-Commands/Terminal-Experience/028-the-history-command.md b/docs/Linux-Commands/Terminal-Experience/028-the-history-command.md new file mode 100755 index 0000000..a9e9fbc --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/028-the-history-command.md @@ -0,0 +1,19 @@ +# The `history` command + +If you type `history` you will get a list of the last 500 commands used. This gives you the possibility to copy and paste commands that you executed in the past. + +This is powerful in combination with grep. So you can search for a command in your command history. + +### Examples: + +1. If you want to search in your history for artisan commands you ran in the past. + +``` +history | grep artisan +``` + +2. If you only want to show the last 10 commands you can. + +``` +history 10 +``` \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/043-the-clear-command.md b/docs/Linux-Commands/Terminal-Experience/043-the-clear-command.md new file mode 100755 index 0000000..1a2e765 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/043-the-clear-command.md @@ -0,0 +1,30 @@ +# The `clear` command + +In linux, the `clear` command is used to clear terminal screen. + +## Example + +```bash +$ clear +``` + +## Before: + +```bash +$ echo Hello World +Hello World + +$ clear +``` +## After executing clear command: +```bash +$ +``` + +Screenshot: + +![clear command in linux example](https://user-images.githubusercontent.com/21223421/135708520-5fb54205-39ce-4e9c-b376-7569d0c4420d.png) + +After running the command your terminal screen will be clear: + +![clear command in linux](https://user-images.githubusercontent.com/21223421/135708538-f01de268-3cf6-4f3a-a32b-a14fb67575f1.png) \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/047-the-yes-command.md b/docs/Linux-Commands/Terminal-Experience/047-the-yes-command.md new file mode 100755 index 0000000..9938db2 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/047-the-yes-command.md @@ -0,0 +1,25 @@ +# The `yes` command + +The `yes` command in linux is used to print a continuous output stream of given _STRING_. If _STRING_ is not mentioned then it prints ‘y’. It outputs a string repeatedly unit killed (using something like ctrl + c). + +### Examples : + +1. Prints hello world infinitely in the terminal until killed : + +``` +yes hello world +``` + +2. A more generalized command: + +``` +yes [STRING] +``` + +## Options +It accepts the following options: + +1. --help + > display this help and exit +2. --version + > output version information and exit diff --git a/docs/Linux-Commands/Terminal-Experience/061-the-exit-command.md b/docs/Linux-Commands/Terminal-Experience/061-the-exit-command.md new file mode 100755 index 0000000..075c9ad --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/061-the-exit-command.md @@ -0,0 +1,10 @@ +# The `exit` command + +The `exit` command is used to terminate (close) an active shell session + +### Syntax: +``` +exit +``` + +***Shortcut:** Instead of typing `exit`, press `ctrl + D`, it will do the same Functionality.* \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/077-the-sleep-command.md b/docs/Linux-Commands/Terminal-Experience/077-the-sleep-command.md new file mode 100755 index 0000000..8ee9648 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/077-the-sleep-command.md @@ -0,0 +1,31 @@ +# The `sleep` command + +The `sleep` command is used to create a dummy job. A dummy job helps in delaying the execution. It takes time in seconds by default but a small suffix(s, m, h, d) can be added at the end to convert it into any other format. This command pauses the execution for an amount of time which is defined by NUMBER. + +Note: If you will define more than one NUMBER with sleep command then this command will delay for the sum of the values. + + +### Examples : + +1. To sleep for 10s + +``` +sleep 10s +``` + +2. A more generalized command: + +``` +sleep NUMBER[SUFFIX]... +``` + +## Options + It accepts the following options: + +1. --help + > display this help and exit +2. --version + > output version information and exit + + +--- diff --git a/docs/Linux-Commands/Terminal-Experience/092-the-xargs-command.md b/docs/Linux-Commands/Terminal-Experience/092-the-xargs-command.md new file mode 100755 index 0000000..2789bd0 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/092-the-xargs-command.md @@ -0,0 +1,90 @@ +# The `xargs` command + +`xargs` is used to build and execute command lines from standard input + +Some commands like grep can accept input as parameters, but some commands accepts arguments, this is place where xargs came into picture. +### Syntax: + +``` +xargs [options] [command [initial-arguments]] +``` + +### Options: + +``` +-0, --null +``` + +Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literal‐ly). Disables the end of file string, which is treated like any other argument. Useful when input items might contain white space, quote marks, or back‐slashes. + + +``` +-a file, --arg-file=file +``` + +Read items from file instead of standard input. If you use this option, stdin remains unchanged when commands are run. Otherwise, stdin is redirected +from /dev/null. + + +``` +-o, --open-tty +``` + +Reopen stdin as /dev/tty in the child process before executing the command. This is useful if you want xargs to run an interactive application. + + +``` +--delimiter=delim, -d delim +``` + +Input items are terminated by the specified character. The specified delimiter may be a single character, a C-style character escape such as \n, or an +octal or hexadecimal escape code. Octal and hexadecimal escape codes are understood as for the printf command. Multibyte characters are not supported. +When processing the input, quotes and backslash are not special; every character in the input is taken literally. The -d option disables any end-of-file +string, which is treated like any other argument. You can use this option when the input consists of simply newline-separated items, although it is al‐ +most always better to design your program to use --null where this is possible. + +``` +-p, --interactive +``` + +Prompt the user about whether to run each command line and read a line from the terminal. Only run the command line if the response starts with `y' or +`Y'. Implies -t. + + +### Examples: + + + ``` + find /tmp -name core -type f -print | xargs /bin/rm -f + ``` +Find files named core in or below the directory /tmp and delete them. Note that this will work incorrectly if there are any filenames containing newlines or +spaces. + + +``` +find /tmp -name core -type f -print0 | xargs -0 /bin/rm -f +``` +Find files named core in or below the directory /tmp and delete them, processing filenames in such a way that file or directory names containing spaces or new‐ +lines are correctly handled. + + +``` +find /tmp -depth -name core -type f -delete +``` + +Find files named core in or below the directory /tmp and delete them, but more efficiently than in the previous example (because we avoid the need to use fork(2) +and exec(2) to launch rm and we don't need the extra xargs process). + + +``` +cut -d: -f1 < /etc/passwd | sort | xargs echo +``` + +Generates a compact listing of all the users on the system. + + +### Help Command +Run below command to view the complete guide to `xargs` command. +``` +man xargs +``` \ No newline at end of file diff --git a/docs/Linux-Commands/Terminal-Experience/107-the-grep-command.md b/docs/Linux-Commands/Terminal-Experience/107-the-grep-command.md new file mode 100755 index 0000000..817f67c --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/107-the-grep-command.md @@ -0,0 +1,62 @@ +# The `grep` command + +The `grep` filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern. +grep stands for globally search for regular expression and print out. The pattern that is searched in the file is referred to as the regular expression. + +### Examples: + +1. To search the contents of the destination.txt file for a string("KeY") case insensitively. + +``` +grep -i "KeY" destination.txt +``` + +2. Displaying the count of number of matches + +``` +grep -c "key" destination.txt +``` + +3. We can search multiple files and only display the files that contains the given string/pattern. + +``` +grep -l "key" destination1.txt destination2.txt destination3.xt destination4.txt +``` + +4. To show the line number of file with the line matched. + +``` +grep -n "key" destination.txt +``` + +5. If you want to grep the monitored log files, you can add the `--line-buffered` to search them in real time. + +``` +tail -f destination.txt | grep --line-buffered "key" +``` + +### Syntax: + +The general syntax for the grep command is as follows: + +``` +grep [options] pattern [files] +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :------------- | :--------------------- | :---------------------------------------------------------------------------------------------- | +| `-c` | `--count` | print a count of matching lines for each input file | +| `-h` | `--no-filename` | Display the matched lines, but do not display the filenames | +| `-i` | `--ignore-case` | Ignores, case for matching | +| `-l` | `--files-with-matches` | Displays list of a filenames only. | +| `-n` | `--line-number` | Display the matched lines and their line numbers. | +| `-v` | `--invert-match` | This prints out all the lines that do not matches the pattern | +| `-e` | `--regexp=` | Specifies expression with this option. Can use multiple times | +| `-f` | `--file=` | Takes patterns from file, one per line. | +| `-F` | `--fixed-strings=` | Interpret patterns as fixed strings, not regular expressions. | +| `-E` | `--extended-regexp` | Treats pattern as an extended regular expression (ERE) | +| `-w` | `--word-regexp` | Match whole word | +| `-o` | `--only-matching` | Print only the matched parts of a matching line, with each such part on a separate output line. | +| | `--line-buffered` | Force output to be line buffered. | diff --git a/docs/Linux-Commands/Terminal-Experience/113-the-alias-command.md b/docs/Linux-Commands/Terminal-Experience/113-the-alias-command.md new file mode 100755 index 0000000..83c15dd --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/113-the-alias-command.md @@ -0,0 +1,58 @@ +# The `alias` command + +The `alias` command lets you create shortcuts for commands or define your own commands. +This is mostly used to avoid typing long commands. + +### Examples: + +1. To show the list of all defined aliases in the reusable form `alias NAME=VALUE` : + +``` +alias -p +``` + +2. To make `ls -A` shortcut: + +``` +alias la='ls -A' +``` + +### Syntax: + +``` +alias [-p] [name[=value]] +``` + +### Setting Persistent Options: + +As with most Linux custom settings for the terminal, any alias you defined is only applied to the current opening terminal session. + +For any alias to be active for all new sessions you need to add that command to your rc file to be executed in the startup of every new terminal. +this file can be as follows: +- **Bash**: ~/.bashrc +- **ZSH**: ~/.zshrc +- **Fish** – ~/.config/fish/config.fish + +you can open that file with your favorite editor as follows: + +``` +vim ~/.bashrc +``` +type your commands one per line, then save the file and exit. +the commands will be automatically applied in the next session. + +If you want to apply it in the current session, run the following command: +``` +source ~/.bashrc +``` + +### Opposite command: +To remove predefined alias you can use `unalias` command as follows: +``` +unalias alias_name +``` + +to remove all aliases +``` +unalias -a +``` diff --git a/docs/Linux-Commands/Terminal-Experience/132-the-less-command.md b/docs/Linux-Commands/Terminal-Experience/132-the-less-command.md new file mode 100755 index 0000000..5de13a4 --- /dev/null +++ b/docs/Linux-Commands/Terminal-Experience/132-the-less-command.md @@ -0,0 +1,45 @@ +# The `less` command + +The less command is a Linux terminal pager which shows a file's content one screen at a time. +Useful when dealing with a large text file because it doesn't load the entire file but accesses it page by page, resulting in fast loading speeds. +## Syntax +``` +less [options] file_path +``` + +## Options +Some popular option flags include: +``` +-E less automatically exits upon reaching the end of file. +-f Forces less to open non-regular files (a directory or a device-special file). +-F Exit less if the entire file can be displayed on the first screen. +-g Highlights the string last found using search. By default, less highlights all strings matching the last search command. +-G Removes all highlights from strings found using search. +``` +For a complete list of options, refer to the less help file by running: +``` + less --help +``` +## Few Examples: +1. Open a Text File +``` +less /etc/updatedb.conf +``` + +2. Show Line Numbers +``` +less -N /etc/init/mysql.conf +``` + +3. Open File with Pattern Search +``` +less -pERROR /etc/init/mysql.conf +``` +4. Remove Multiple Blank Lines +``` +less welcome.txt +``` + +Here I showed you how to use the less command in Linux. Although there are other terminal pagers, such as most and more, but less could be a better choice as it is a powerful tool present in almost every system. + +For more details: https://phoenixnap.com/kb/less-command-in-linux#:~:text=The%20less%20command%20is%20a,resulting%20in%20fast%20loading%20speeds. \ No newline at end of file diff --git a/docs/Linux-Commands/Users-And-Groups/023-the-groups-command.md b/docs/Linux-Commands/Users-And-Groups/023-the-groups-command.md new file mode 100755 index 0000000..d3d4aa9 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/023-the-groups-command.md @@ -0,0 +1,45 @@ +# The `groups` command + +In Linux, there can be multiple users (those who use/operate the system), and groups (a collection of users). +Groups make it easy to manage users with the same security and access privileges. A user can be part of different groups. + +Important Points: + +The `groups` command prints the names of the primary and any supplementary groups for each given username, or the current process if no names are given. +If more than one name is given, the name of each user is printed before the list of that user’s groups and the username is separated from the group list by a colon. + +### Syntax: + +``` +groups [username] +``` + +#### Example 1 + +Provided with a username + +``` +groups demon +``` + +In this example, username demon is passed with groups command and the output shows the groups in which the user demon is present, separated by a colon. + +#### Example 2 + +When no username is passed then this will display the group membership for the current user: + +``` +groups +``` + +Here the current user is demon . So when we run the `groups` command without arguments we get the groups in which demon is a user. + +#### Example 3 + +Passing root with groups command: + +``` +$demon# groups +``` + +> Note: Primary and supplementary groups for a process are normally inherited from its parent and are usually unchanged since login. This means that if you change the group database after logging in, groups will not reflect your changes within your existing login session. The only options are –help and –version. diff --git a/docs/Linux-Commands/Users-And-Groups/025-the-passwd-command.md b/docs/Linux-Commands/Users-And-Groups/025-the-passwd-command.md new file mode 100755 index 0000000..d72fc2a --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/025-the-passwd-command.md @@ -0,0 +1,55 @@ + +# The `passwd` command + +In Linux, `passwd` command changes the password of user accounts. A normal user may only change the password for their own account, but a superuser may change the password for any account. +`passwd` also changes the account or associated password validity period. + + +## Example + +```bash +$ passwd + +``` + + +## The syntax of the `passwd` command is : + +```bash +$ passwd [options] [LOGIN] + +``` +## options + +```bash +-a, --all + This option can be used only with -S and causes show status for all users. + +-d, --delete + Delete a user's password. + +-e, --expire + Immediately expire an account's password. + +-h, --help + Display help message and exit. + +-i, --inactive + This option is used to disable an account after the password has been expired for a number of days. + +-k, --keep-tokens + Indicate password change should be performed only for expired authentication tokens (passwords). + +-l, --lock + Lock the password of the named account. + +-q, --quiet + Quiet mode. + +-r, --repository + change password in repository. + +-S, --status + Display account status information. + +``` diff --git a/docs/Linux-Commands/Users-And-Groups/027-the-whoami-command.md b/docs/Linux-Commands/Users-And-Groups/027-the-whoami-command.md new file mode 100755 index 0000000..a617033 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/027-the-whoami-command.md @@ -0,0 +1,58 @@ +# The `whoami` command +--- +The `whoami` command displays the username of the current effective user. In other words it just prints the username of the currently logged-in user when executed. + +To display your effective user id just type `whoami` in your terminal: + +``` +manish@godsmack:~$ whoami +# Output: +manish +``` + +Syntax: + +``` +whoami [-OPTION] +``` + +There are only two options which can be passed to it : + +`--help`: Used to display the help and exit + +Example: + +``` +whoami --help +``` + +Output: + +``` +Usage: whoami [OPTION]... +Print the user name associated with the current effective user ID. +Same as id -un. + + --help display this help and exit + --version output version information and exit +``` + +`--version`: Output version information and exit + +Example: + +``` +whoami --version +``` + +Output: + +``` +whoami (GNU coreutils) 8.32 +Copyright (C) 2020 Free Software Foundation, Inc. +License GPLv3+: GNU GPL version 3 or later . +This is free software: you are free to change and redistribute it. +There is NO WARRANTY, to the extent permitted by law. + +Written by Richard Mlynarik. +``` \ No newline at end of file diff --git a/docs/Linux-Commands/Users-And-Groups/080-the-useradd-command.md b/docs/Linux-Commands/Users-And-Groups/080-the-useradd-command.md new file mode 100755 index 0000000..c4e59b8 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/080-the-useradd-command.md @@ -0,0 +1,43 @@ +# The `useradd` command + +The `useradd` command is used to add or update user accounts to the system. + +### Examples: + +To add a new user with the `useradd` command the syntax would be the following: + +``` +useradd NewUser +``` + +To add a new user with the `useradd` command and give a home directory path for this new user the syntax would be the following: + +``` +useradd -d /home/NewUser NewUser +``` + +To add a new user with the `useradd` command and give it a specific id the syntax would be the following: + +``` +useradd -u 1234 NewUser +``` + +### Syntax: + +``` +useradd [OPTIONS] NameOfUser +``` + +### Possible options: + +|**Flag** |**Description** |**Params** | +|:---|:---|:---| +|`-d`|The new user will be created using /path/to/directory as the value for the user's login directory|/path/to/directory| +|`-u`|The numerical value of the user's ID|ID| +|`-g`|Create a user with specific group id|GroupID| +|`-M`|Create a user without home directory|-| +|`-e`|Create a user with expiry date|DATE (format: YYYY-MM-DD)| +|`-c`|Create a user with a comment|COMMENT| +|`-s`|Create a user with changed login shell|/path/to/shell| +|`-p`|Set an unencrypted password for the user|PASSWORD| + diff --git a/docs/Linux-Commands/Users-And-Groups/082-the-usermod-command.md b/docs/Linux-Commands/Users-And-Groups/082-the-usermod-command.md new file mode 100755 index 0000000..27b610e --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/082-the-usermod-command.md @@ -0,0 +1,80 @@ +# The `usermod` command + +The `usermod` command lets you change the properties of a user in Linux through the command line. After creating a user we sometimes have to change their attributes, like their password or login directory etc. So in order to do that we use the `usermod` command. + +### Syntax: + +``` +usermod [options] USER +``` + +#### Note : Only superuser (root) is allowed to execute `usermod` command + +### Options and their Functionalities: + +|**Option** |**Description** | +|:---|:---| +|`-a`|to add anyone of the group to a secondary group| +|`-c`|to add comment field for the useraccount| +|`-d`|to modify the directory for any existing user account| +|`-g`|change the primary group for a User| +|`-G`|to add supplementary groups| +|`-l`|to change existing user login name| +|`-L`|to lock system user account| +|`-m`|to move the contents of the home directory from existing home dir to new dir| +|`-p`|to create an un-encrypted password| +|`-s`|to create a specified shell for new accounts| +|`-u`|to assigned UID for the user account| +|`-U`|to unlock any locked user| + +### Examples: + +1. To add a comment/description for a user: +``` +sudo usermod -c "This is test user" test_user +``` + +2. To change the home directory of a user: +``` +sudo usermod -d /home/sam test_user +``` + +3. To change the expiry date of a user: +``` +sudo usermod -e 2021-10-05 test_user +``` + +4. To change the group of a user: +``` +sudo usermod -g sam test_user +``` + +5. To change user login name: +``` +sudo usermod -l test_account test_user +``` + +6. To lock a user: +``` +sudo usermod -L test_user +``` + +7. To unlock a user: +``` +sudo usermod -U test_user +``` + +8. To set an unencrypted password for the user: +``` +sudo usermod -p test_password test_user +``` + +9. To create a shell for the user: +``` +sudo usermod -s /bin/sh test_user +``` + +10. To change the user id of a user: +``` +sudo usermod -u 1234 test_user +``` diff --git a/docs/Linux-Commands/Users-And-Groups/101-the-chown-command.md b/docs/Linux-Commands/Users-And-Groups/101-the-chown-command.md new file mode 100755 index 0000000..40c494b --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/101-the-chown-command.md @@ -0,0 +1,36 @@ +# The `chown` command + +The `chown` command makes it possible to change the ownership of a file or directory. Users and groups are fundamental in Linux, with `chown` you can +change the owner of a file or directory. It's also possible to change ownership on folders recursively + +### Examples: + +1. Change the owner of a file + +``` +chown user file.txt +``` + +2. Change the group of a file + +``` +chown :group file.txt +``` + +3. Change the user and group in one line + +``` +chown user:group file.txt +``` + +4. Change to ownership on a folder recursively + +``` +chown -R user:group folder +``` + +### Syntax: + +``` +chown [-OPTION] [DIRECTORY_PATH] +``` \ No newline at end of file diff --git a/docs/Linux-Commands/Users-And-Groups/106-the-chmod-command.md b/docs/Linux-Commands/Users-And-Groups/106-the-chmod-command.md new file mode 100755 index 0000000..d5d4136 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/106-the-chmod-command.md @@ -0,0 +1,67 @@ +# The `chmod` command + +The `chmod` command allows you to change the permissions on a file using either a symbolic or numeric mode or a reference file. + +### Examples: + +1. Change the permission of a file using symbolic mode: + +``` +chmod u=rwx,g=rx,o=r myfile +``` + +The command above means : + +- user can read, write, execute `myfile` +- group can read, execute `myfile` +- other can read `myfile` + +2. Change the permission of a file using numeric mode + +``` +chmod 754 myfile user:group file.txt +``` + +The command above means : + +- user can read, write, execute `myfile` +- group can read, execute `myfile` +- other can read `myfile` + +3. Change the permission of a folder recursively + +``` +chmod -R 754 folder +``` + +### Syntax: + +``` +chmod [OPTIONS] MODE FILE(s) +``` + +- `[OPTIONS]` : + `-R`: recursive, mean all file inside directory + +- `MODE`: different way to set permissions: + +- **Symbolic mode explained** + + - u: user + - g: group + - o: other + - =: set the permission + - r: read + - w: write + - x: execute + - example `u=rwx` means user can read write and execute + +- **Numeric mode explained**: + +The **numeric mode** is based off of a binary representation of the permissions for user, group, and others, for more information please look at this [explanation](https://www.digitalocean.com/community/tutorials/linux-permissions-basics-and-how-to-use-umask-on-a-vps#types-of-permissions) from Digital Ocean's community section: + + - 4 stands for "read", + - 2 stands for "write", + - 1 stands for "execute", and + - 0 stands for "no permission." + - example 7 mean read + write + execute diff --git a/docs/Linux-Commands/Users-And-Groups/the-deluser-command.md b/docs/Linux-Commands/Users-And-Groups/the-deluser-command.md new file mode 100755 index 0000000..5c62925 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/the-deluser-command.md @@ -0,0 +1,40 @@ +# The `deluser` command + +The `deluser` command is used to delete a user account and related files + +## Command Demo + + + +## Delete User + +To delete a user with the `deluser` command the syntax would be the following: + +``` +deluser userName +``` + +## Delete User & Home Directory + +To delete a user along with the files in the user’s home directory using the `deluser` command the syntax would be the following: + +``` +deluser --remove-home userName +``` + +## Basic Syntax: + +``` +deluser [options] [--force] [--remove-home] [--remove-all-files] + [--backup] [--backup-to DIR] user + +``` + +## Possible Options: + +|**Flag** |**Description** | +|:---|:---| +|`-f`|Force the removal of the specified user account even if the user is logged in| +|`-r`|Remove the files in the user’s home directory along with the home directory itself and the user’s mail spool| +|`-Z`|Remove any SELinux(Security-Enhanced Linux) user mapping for the user’s login.| + diff --git a/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.kdenlive b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.kdenlive new file mode 100755 index 0000000..02498a4 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.kdenlive @@ -0,0 +1,298 @@ + + + + + 833 + pause + the-deluser-command.ogv + 2 + video + -nan + 1 + 1280 + 816 + 0 + 15 + yuv420p + 1 + 709 + theora + Theora + 0 + 0.3.8.1 + 1 + 1 + 1 + 1 + -1 + 1 + 0 + avformat-novalidate + + 15 + 1 + 709 + 2 + 1280 + 816 + mpeg + 0 + 1 + -1 + 2 + 3922697 + d5c20e7b918aa4a4201d897c2444414e + 1 + + + 2 + -1 + . + 0 + 1723562956277 + 0 + 0 + 0 + + 0 + 0 + [ +] + + 19.12.3 + 678 + + + /home/softwareshinobi/.local/share/kdenlive/profiles/customprofile0 + + 2000 + 800 + 1000 + + 2982 + 30000 + 0.99 + 1 + 2 + 0 + 75 + 3 + + 1 + + + + 2147483647 + continue + black + 1 + color + rgb24a + 0 + + + 1 + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + + 1 + + + 1 + 66 + 0 + + + + + + + 0 + audiolevel + + + + 1 + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + + 1 + + + 1 + 66 + 0 + + + 1 + + + + 0 + audiolevel + + + + 833 + pause + the-deluser-command.ogv + -1 + 1 + 0 + avformat-novalidate + 1 + 1 + + -1 + 2 + 3922697 + d5c20e7b918aa4a4201d897c2444414e + 1 + was here + 2 + video + -nan + 1 + 1280 + 816 + 0 + 15 + yuv420p + 1 + 709 + theora + Theora + 0 + 0.3.8.1 + 1 + 1 + 15 + 1 + 709 + 2 + 1280 + 816 + mpeg + 0 + 1 + 1 + 0 + + + + 2 + + + + + 66 + 0 + + + 1 + + + + + + + 66 + 0 + + + + + + + + + + + + + + 0 + 1 + mix + mix + 237 + 1 + 1 + + + 0 + 2 + mix + mix + 237 + 1 + 1 + + + 0 + 3 + 0 + 0 + 0 + qtblend + qtblend + 237 + 1 + + + 0 + 4 + 0 + 0 + 0 + qtblend + qtblend + 237 + 1 + + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + 0 + audiolevel + + + diff --git a/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.mp4 b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.mp4 new file mode 100755 index 0000000..56c96d1 Binary files /dev/null and b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.mp4 differ diff --git a/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.ogv b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.ogv new file mode 100755 index 0000000..489ea0e Binary files /dev/null and b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command.ogv differ diff --git a/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command_backup0.kdenlive b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command_backup0.kdenlive new file mode 100755 index 0000000..0bcd5f1 --- /dev/null +++ b/docs/Linux-Commands/Users-And-Groups/the-deluser-command/the-deluser-command_backup0.kdenlive @@ -0,0 +1,298 @@ + + + + + 833 + pause + out.ogv + 2 + video + -nan + 1 + 1280 + 816 + 0 + 15 + yuv420p + 1 + 709 + theora + Theora + 0 + 0.3.8.1 + 1 + 1 + 1 + 1 + -1 + 1 + 1 + avformat + + 2 + 15 + 1 + 709 + 2 + 1280 + 816 + mpeg + 0 + 1 + 3922697 + d5c20e7b918aa4a4201d897c2444414e + -1 + 1 + + + 2 + -1 + . + 0 + 1723562956277 + 0 + 0 + 0 + + 0 + 0 + 19.12.3 + 91 + + + /home/softwareshinobi/.local/share/kdenlive/profiles/customprofile0 + + 2000 + 800 + 1000 + + 0 + 30000 + 0.99 + 1 + 2 + 0 + 75 + 8 + + [ +] + + 1 + + + + 2147483647 + continue + black + 1 + color + rgb24a + 0 + + + 1 + + + 1 + + + 1 + 66 + 0 + + + + + + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + 0 + audiolevel + + + + 1 + + + 1 + + + 1 + 66 + 0 + + + 1 + + + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + 0 + audiolevel + + + + 833 + pause + out.ogv + 2 + video + -nan + 1 + 1280 + 816 + 0 + 15 + yuv420p + 1 + 709 + theora + Theora + 0 + 0.3.8.1 + 1 + 1 + 1 + 1 + -1 + 1 + 0 + avformat-novalidate + + 2 + 3922697 + d5c20e7b918aa4a4201d897c2444414e + -1 + 1 + was here + 15 + 1 + 709 + 2 + 1280 + 816 + mpeg + 0 + 1 + 1 + 0 + + + + 2 + + + + + 66 + 0 + + + 1 + + + + + + + 66 + 0 + + + + + + + + + + + + + + 0 + 1 + mix + mix + 237 + 1 + 1 + + + 0 + 2 + mix + mix + 237 + 1 + 1 + + + 0 + 3 + 0 + 0 + 0 + qtblend + qtblend + 237 + 1 + + + 0 + 4 + 0 + 0 + 0 + qtblend + qtblend + 237 + 1 + + + 75 + 20dB + volume + 237 + 1 + + + -1 + panner + 237 + 0.5 + 1 + + + 0 + audiolevel + + + diff --git a/docs/Linux-Commands/Working-With-Files/001-the-ls-command.md b/docs/Linux-Commands/Working-With-Files/001-the-ls-command.md new file mode 100755 index 0000000..4e30f8f --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/001-the-ls-command.md @@ -0,0 +1,71 @@ +# The `ls` command + +The `ls` command lets you see the files and directories inside a specific directory *(current working directory by default)*. +It normally lists the files and directories in ascending alphabetical order. + +### Examples: + +1. To show the files inside your current working directory: + +``` +ls +``` + +2. To show the files and directory inside a specific Directory: + +``` +ls {Directory_Path} +``` + +### Syntax: + +``` +ls [-OPTION] [DIRECTORY_PATH] +``` + +### Interactive training + +In this interactive tutorial, you will learn the different ways to use the `ls` command: + +[The ls command by Tony](https://devdojo.com/tnylea/ls-command) + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-l`|
-
|Show results in long format| +|`-S`|
-
|Sort results by file size| +|`-t`|
-
|Sort results by modification time| +|`-r`|`--reverse`|Show files and directories in reverse order *(descending alphabetical order)*| +|`-a`|`--all`|Show all files, including hidden files *(file names which begin with a period `.`)*| +|`-la`|
-
|Show long format files and directories including hidden files| +|`-lh`|
-
|list long format files and directories with readable size| +|`-A`|`--almost-all`|Shows all like `-a` but without showing `.`(current working directory) and `..` (parent directory)| +|`-d`|`--directory`|Instead of listing the files and directories inside the directory, it shows any information about the directory itself, it can be used with `-l` to show long formatted information| +|`-F`|`--classify`|Appends an indicator character to the end of each listed name, as an example: `/` character is appended after each directory name listed| +|`-h`|`--human-readable`|like `-l` but displays file size in human-readable unit not in bytes| + + +### Setting Persistent Options: + + +Customizing command behavior in Linux is easy using the `alias` command. To make these changes permanent, follow these steps: + +1. **Create the Alias**: Define your alias with the desired options. For example, to enhance the `ls` command: + + ```bash + alias ls="ls --color=auto -lh" + ``` + +2. **Persistence**: This alias is effective only for the current session. To make it permanent, add the alias to your shell's configuration file: + + - **Bash**: Append the alias to `~/.bashrc`: + + ```bash + echo 'alias ls="ls --color=auto -lh"' >> ~/.bashrc + source ~/.bashrc + ``` + +3. **Verification**: Open a new terminal session, and the `ls` command will display files as configured. + + diff --git a/docs/Linux-Commands/Working-With-Files/003-the-cat-tac-command.md b/docs/Linux-Commands/Working-With-Files/003-the-cat-tac-command.md new file mode 100755 index 0000000..be1ffed --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/003-the-cat-tac-command.md @@ -0,0 +1,153 @@ +# The `cat` command +--- + +The `cat` command allows us to create single or multiple files, to view the content of a file or to concatenate files and redirect the output to the terminal or files. + +The "cat" stands for 'concatenate.' and it's one of the most frequently used commands in the Linux terminal. + + +### Examples of uses: + + +1. To display the content of a file in terminal: + +``` +cat +``` + +2. To display the content of multiple files in terminal: + +``` +cat file1 file2 ... +``` + +3. To create a file with the cat command: + +``` +cat > file_name +``` + +4. To display all files in current directory with the same filetype: + +``` +cat *. +``` + +5. To display the content of all the files in current directory: + +``` +cat * +``` + +6. To put the output of a given file into another file: + +``` +cat old_file_name > new_file_name +``` +7. Use cat command with `more` and `less` options: + +``` +cat filename | more +cat filename | less +``` + +8. Append the contents of file1 to file2: + +``` +cat file1 >> file2 +``` + +9. To concatenate two files together in a new file: + +``` +cat file1_name file2_name merge_file_name +``` + +10. Some implementations of cat, with option -n, it's possible to show line numbers: + +``` +cat -n file1_name file2_name > new_numbered_file_name +``` + + +### Syntax: + +``` +cat [OPTION] [FILE]... +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-A`| `--show-all` |equivalent to -vET| +|`-b`| `--number-nonblank` |number nonempty output lines, overrides -n| +|`-e`|
-
| equivalent to -vE| +|`-T`|
-
|Display tab separated lines in file opened with ```cat``` command.| +|`-E`|
-
|To show $ at the end of each file.| +|`-E`|
-
|Display file with line numbers.| +|`-n`| `--number`|number all output lines| +|`-s`| `--squeeze-blank`|suppress repeated empty output lines| +|`-u`|
-
|(ignored)| +|`-v`| `--show-nonprinting`|use ^ and M- notation, except for LFD and TAB| +|
-
|`--help` |display this help and exit| +|
-
|`--version`|output version information and exit| + + +--- + + +# The `tac` command + +`tac` is a Linux command that allows you to view files line-by-line, beginning from the last line. (tac doesn't reverse the contents of each individual line, only the order in which the lines are presented.) It is named by analogy with `cat`. + + +### Examples of uses: + + +1. To display the content of a file in terminal: + +``` +tac +``` + +2. This option attaches the separator before instead of after. + +``` +tac -b concat_file_name tac_example_file_name +``` +3. This option will interpret the separator as a regular expression. +``` +tac -r concat_file_name tac_example_file_name +``` +4. This option uses STRING as the separator instead of newline. +``` +tac -s concat_file_name tac_example_file_name +``` + +5. This option will display the help text and exit. + +``` +tac --help +``` +6. This option will give the version information and exit. + +``` +tac --version +``` + +### Syntax: + +``` +tac [OPTION]... [FILE]... +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-b`|`--before`|attach the separator before instead of after| +|`-r`| `--regex`|interpret the separator as a regular expression| +|`-s`| `--separator=STRING`|use STRING as the separator instead of newline| +|
-
|`--help`|display this help and exit| +|
-
|`--version`|output version information and exit| diff --git a/docs/Linux-Commands/Working-With-Files/007-the-touch-command.md b/docs/Linux-Commands/Working-With-Files/007-the-touch-command.md new file mode 100755 index 0000000..e03f20b --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/007-the-touch-command.md @@ -0,0 +1,59 @@ +# The `touch` Command +The `touch` command modifies a file's timestamps. If the file specified doesn't exist, an empty file with that name is created. + + +### Syntax +``` +touch [OPTION]... FILE... +``` + +### Options +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-a`|
-
|Change only the access time.| +|`-c`|`--no-create`|Do not create any files.| +|`-d` STRING|`--date=STRING`|Parse *STRING* and use it instead of the current time.| +|`-f`|
-
|(Ignored) This option does nothing but is accepted to provide compatibility with BSD versions of the `touch` command.| +|`-h`|`--no-dereference`|Affect each symbolic link instead of any referenced file (useful only on systems that can change the timestamps of a symlink). This option implies `-c`, nothing is created if the file does not exist.| +|`-m`|
-
|Change only the modification time.| +|`-r=FILE`|`--reference=FILE`|Use this file's times instead of the current time.| +|`-t STAMP`|
-
|Use the numeric time *STAMP* instead of the current time. The format of *STAMP* is [[**CC**]**YY**]**MMDDhhmm**[**.ss**].| +|
-
|`--time=WORD`|An alternate way to specify which type of time is set (e.g. *access*, *modification*, or *change*). This is equivalent to specifying `-a` or `-m`. + +- WORD is `access`, `atime`, or `use`: equivalent to `-a`. +- WORD is `modify` or `mtime`: equivalent to `-m`. + +An alternate way to specify what type of time to set (as with **-a** and **-m**).| +|
-
|`--help`|Display a help message, and exit.| +|
-
|`--version`|Display version information, and exit.| + +### Examples +1. If **file.txt** exists, set all of its timestamps to the current system time. If **file.txt** doesn't exist, create an empty file with that name. +``` +touch file.txt +``` + +2. If **file.txt** exists, set its times to the current system time. If it does not exist, do nothing. +``` +touch -c file.txt +``` + +3. Change the *access* time of **file.txt**. The *modification* time is not changed. The *change* time is set to the current system time. If **file.txt** does not exist, it is created. +``` +touch -a file.txt +``` + +4. Change the times of file **symboliclink**. If it's a symbolic link, change the times of the symlink, ***NOT*** the times of the referenced file. +``` +touch -h symboliclink +``` + +5. Change the *access* and *modification* times of **file-b.txt** to match the times of **file-a.txt**. The *change* time will be set to the current system time. If **file-b.txt** does not exist, it is not created. Note, **file-a.txt** must already exist in this context. +``` +touch -cr file-a.txt file-b.txt +``` + +6. Set the *access* time and *modification* time of **file.txt** to ***February 1st*** of the current year. The *change* time is set to the current system time. +``` +touch -d "1 Feb" file.txt +``` diff --git a/docs/Linux-Commands/Working-With-Files/014-the-mkdir-command.md b/docs/Linux-Commands/Working-With-Files/014-the-mkdir-command.md new file mode 100755 index 0000000..d86d90e --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/014-the-mkdir-command.md @@ -0,0 +1,44 @@ +# The `mkdir` command +The `mkdir` command in Linux/Unix is used to create a directory. + + +## Syntax +```bash +$ mkdir [-m=mode] [-p] [-v] [-Z=context] directory [directory ...] +``` + +## Examples +1. Make a directory named **myfiles**. +```bash +$ mkdir myfiles +``` + +2. Create a directory named **myfiles** at the home directory: +```bash +$ mkdir ~/myfiles +``` + +3. Create the **mydir** directory, and set its file mode (`-m`) so that all users (`a`) may read (`r`), write (`w`), and execute (`x`) it. +```bash +$ mkdir -m a=rwx mydir +``` + +You can also create sub-directories of a directory. It will create the parent directory first, if it doesn't exist. +If it already exists, then it move further to create the sub-directories without any error message. + +For directories, this means that any user on the system may view ("read"), and create/modify/delete ("write") files in the directory. Any user may also change to ("execute") the directory, for example with the `cd` command. + +4. Create the directory **/home/test/src/python**. If any of the parent directories **/home**, **/home/test**, or **/home/test/src** do not already exist, they are automatically created. +```bash +$ mkdir -p /home/test/src/python +``` + +## Options +|**Short Flags**|**Long Flags**|**Descriptions**| +|:-|:-|:-| +|`-m`|`--mode=MODE`|Set file mode (as in chmod), not `a=rwx - umask`.| +|`-p`|`--parents`|No error if existing, make parent directories as needed.| +|`-v`|`--verbose`|Print a message for each created directory.| +|`-Z`|`--context=CTX`|Set the SELinux security context of each created directory to CTX.| +|
-
|`--help`|Display a help message and exit.| +|
-
|`--version`|Output version information and exit.| diff --git a/docs/Linux-Commands/Working-With-Files/031-the-cp-command.md b/docs/Linux-Commands/Working-With-Files/031-the-cp-command.md new file mode 100755 index 0000000..128abc2 --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/031-the-cp-command.md @@ -0,0 +1,103 @@ +# The `cp` command + +The `cp` is a command-line utility for copying files and directory. +`cp` stands for copy. This command is used to copy files or group of files or directory. It creates an exact image of a file on a disk with different file name. The cp command requires at least two filenames in its arguments. + +### Examples: + +1. To copy the contents of the source file to the destination file. + +``` +cp sourceFile destFile +``` + +If the destination file doesn't exist then the file is created and the content is copied to it. If it exists then the file is overwritten. + +2. To copy a file to another directory specify the absolute or the relative path to the destination directory. + +``` +cp sourceFile /folderName/destFile +``` + +3. To copy a directory, including all its files and subdirectories + +``` +cp -R folderName1 folderName2 +``` + +The command above creates the destination directory and recursively copies all files and subdirectories from the source to the destination directory. + +If the destination directory already exists, the source directory itself and its content are copied inside the destination directory. + +4. To copy only the files and subdirectories but not the source directory + +``` +cp -RT folderName1 folderName2 +``` + +### Syntax: + +The general syntax for the cp command is as follows: + +``` +cp [OPTION] SOURCE DESTINATION +cp [OPTION] SOURCE DIRECTORY +cp [OPTION] SOURCE-1 SOURCE-2 SOURCE-3 SOURCE-n DIRECTORY +``` + +The first and second syntax is used to copy Source file to Destination file or Directory. +The third syntax is used to copy multiple Sources(files) to Directory. + +#### Some useful options + +1. `-i` (interactive) + `i` stands for Interactive copying. With this option system first warns the user before overwriting the destination file. cp prompts for a response, if you press y then it overwrites the file and with any other option leave it uncopied. + +``` +$ cp -i file1.txt fileName2.txt +cp: overwrite 'file2.txt'? y +``` + +2. `-b`(backup) + -b(backup): With this option cp command creates the backup of the destination file in the same folder with the different name and in different format. + +``` +$ ls +a.txt b.txt + +$ cp -b a.txt b.txt + +$ ls +a.txt b.txt b.txt~ +``` + +3. `-f`(force) + If the system is unable to open destination file for writing operation because the user doesn't have writing permission for this file then by using -f option with cp command, destination file is deleted first and then copying of content is done from source to destination file. +``` +$ ls -l b.txt +-r-xr-xr-x+ 1 User User 3 Nov 24 08:45 b.txt +``` +User, group and others doesn't have writing permission. + +Without `-f` option, command not executed + +``` +$ cp a.txt b.txt +cp: cannot create regular file 'b.txt': Permission denied +``` + +With -f option, command executed successfully +``` +$ cp -f a.txt b.txt +``` + +### Additional Flags and their Functionalities: + +|**Short Flag** |**Long Flag** |**Description** | +|:---|:---|:---| +|`-i`|
--interactive
|prompt before overwrite| +|`-f`|
--force
|If an existing destination file cannot be opened, remove it and try again| +|`-b`|
-
|Creates the backup of the destination file in the same folder with the different name and in different format.| +|`-r or -R`|`--recursive`|**cp** command shows its recursive behavior by copying the entire directory structure recursively.| +|`-n`|`--no-clobber`|do not overwrite an existing file (overrides a previous -i option)| +|`-p`|
-
|preserve the specified attributes (default: mode,ownership,timestamps), if possible additional attributes: context, links, xattr, all| diff --git a/docs/Linux-Commands/Working-With-Files/032-the-mv-command.md b/docs/Linux-Commands/Working-With-Files/032-the-mv-command.md new file mode 100755 index 0000000..39f6eda --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/032-the-mv-command.md @@ -0,0 +1,46 @@ +# The `mv` command + +The `mv` command lets you **move one or more files or directories** from one place to another in a file system like UNIX. +It can be used for two distinct functions: + +- To rename a file or folder. +- To move a group of files to a different directory. + +_**Note:** No additional space is consumed on a disk during renaming, and the mv command doesn't provide a prompt for confirmation_ + +### Syntax: + +```[linux] +mv [options] source (file or directory) destination +``` + +### Examples: + +1. To rename a file called old_name.txt: + +```[linux] +mv old_name.txt new_name.txt +``` + +2. To move a file called _essay.txt_ from the current directory to a directory called _assignments_ and rename it _essay1.txt_: + +```[linux] +mv essay.txt assignments/essay1.txt +``` + +3. To move a file called _essay.txt_ from the current directory to a directory called _assignments_ without renaming it + +```[linux] +mv essay.txt assignments +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :------------- | :-------------- | :-------------------------------------------------------------------------------------------------------- | +| `-f` | `--force` | Force move by overwriting destination file without prompt | +| `-i` | `--interactive` | Interactive prompt before overwrite | +| `-u` | `--update` | Move only when the source file is newer than the destination file or when the destination file is missing | +| `-n` | `--no-clobber` | Do not overwrite an existing file | +| `-v` | `--verbose` | Print source and destination files | +| `-b` | `--backup` | Create a Backup of Existing Destination File | diff --git a/docs/Linux-Commands/Working-With-Files/039-the-nano-command.md b/docs/Linux-Commands/Working-With-Files/039-the-nano-command.md new file mode 100755 index 0000000..9e524fd --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/039-the-nano-command.md @@ -0,0 +1,51 @@ +# The `nano` command + +The `nano` command lets you create/edit text files. + +### Installation: + +Nano text editor is pre-installed on macOS and most Linux distros. It's an alternative to `vi` and `vim`. To check if it is installed on your system type: + +``` +nano --version +``` +If you don't have `nano` installed you can do it by using the package manager: + +Ubuntu or Debian: + +``` +sudo apt install nano +``` + +### Examples: + +1. Open an existing file, type `nano` followed by the path to the file: + +``` +nano /path/to/filename +``` + +2. Create a new file, type `nano` followed by the filename: + +``` +nano filename +``` + +3. Open a file with the cursor on a specific line and character use the following syntax: + +``` +nano +line_number,character_number filename +``` + +### Overview of some Shortcuts and their Functionalities: + +|**Shortcut** |**Description** | +|:---|:---| +|`Ctrl + S`|Save current file| +|`Ctrl + O`|Offer to write file ("Save as")| +|`Ctrl + X`|Close buffer, exit from nano| +|`Ctrl + K`|Cut current line into cutbuffer| +|`Ctrl + U`|Paste contents of cutbuffer| +|`Alt + 6`|Copy current line into cutbuffer| +|`Alt + U`|Undo last action| +|`Alt + E`| Redo last undone action| diff --git a/docs/Linux-Commands/Working-With-Files/040-the-rm-command.md b/docs/Linux-Commands/Working-With-Files/040-the-rm-command.md new file mode 100755 index 0000000..9daf75b --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/040-the-rm-command.md @@ -0,0 +1,36 @@ +# The `rm` command + +`rm` which stands for "remove" is a command used to remove *(delete)* specific files. It can also be used to remove directories by using the appropriate flag. + +### Example: +``` +rm filename.txt +``` +### Syntax +``` +rm [OPTION] [FILE|DIRECTORY] +``` + +### Flags and their Functionalities: +|Short Flag|Long Flag|Description| +|:---|:---|:---| +|`-f`|`--force`|Ignore nonexistance of files or directories, never prompt| +|`-i`|
-
|Prompt before every removal| +|`-I`|
-
|Prompt once before removal of more than 3 files, or when removing recursively| +|`-d`|`--dir`|remove empty directories| +|`-v`|`--verbose`|explain what is being done| +|`-r` or `-R`|`--recursive`|remove directories and their contents recursively| +|
-
|`--help`|Display help then exit| +|
-
|`--version`|First, Print version Information, Then exit| +|
-
|`--no-preserve-root`|do not treat `/` specially| +|
-
|`-preserve-root[=all]`|do not remove `/` (default)
with 'all', reject any command line argument on a separate device from its parent| +|
-
|`--interactive[=WHEN]`|prompt according to WHEN, never, once `-I`, or always `-i`, without WHEN, prompt always| +|
-
|` --one-file-system`|when removing a hierarchy recursively, skip any directory that is on a file system different from that of the corresponding command line argument0| + + +***IMPORTANT NOTICE:*** +1. `rm` doesn't remove directories by default, so use `-r`, `-R`, `--recursive` options to remove each listed directory, along with all of its contents. +2. To remove a file whose name starts with `-` such as `-foo`, use one of the following commands: + - `rm -- -foo` + - `rm ./-foo` +3. To ensure that files/directories being deleted are truly unrecoverable, consider using the `shred` command. \ No newline at end of file diff --git a/docs/Linux-Commands/Working-With-Files/057-the-dir-command.md b/docs/Linux-Commands/Working-With-Files/057-the-dir-command.md new file mode 100755 index 0000000..6a874de --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/057-the-dir-command.md @@ -0,0 +1,44 @@ +# The `dir` command + +The `dir` command lists the contents of a directory(_the current directory by default_). **It differs from ls command in the format of listing the content**. By default, the dir command lists the files and folders in columns, sorted vertically and special characters are represented by backslash escape sequences. + +### Syntax: + +```[linux] +dir [OPTIONS] [FILE] +``` + +### Examples: + +1. To list files in the current directory: + +```[linux] +dir +``` + +2. To list even the hidden files in the current directory: + +```[linux] +dir -a +``` + +3. To list the content with detailed information for each entry + +```[linux] +dir -l +``` + +### Additional Flags and their Functionalities: + +| **Short Flag** | **Long Flag** | **Description** | +| :----------------- | :-------------------------- | :-------------------------------------------------------------------------------------------------------------------------------- | +| `-a` | `--all` | It displays all the hidden files(starting with `.`) along with two files denoted by `.` and `..` | +| `-A` | `--almost-all` | It is **similar to -a** option except that it _does not display files that signals the current directory and previous directory._ | +| `-l` |
-
| Display detailed information for each entry | +| `-s` | `--size` | Print the allocated size of each file, in blocks File | +| `-h` | `--human-readable` | Used with with -l and -s, to print sizes like in human readable format like 1K, 2M and so on | +| `-F` |
-
| Classifies entries into their type based on appended symbol (`/`, `*`, `@`, `%`, `=`) | +| `-v` | `--verbose` | Print source and destination files | +|
-
| `--group-directories-first` | To group directories before files | +| `-R ` | `--recursive` | To List subdirectories recursively. | +| `-S ` |
-
| sort by file size, display largest first | diff --git a/docs/Linux-Commands/Working-With-Files/062-the-diff-sdiff-command.md b/docs/Linux-Commands/Working-With-Files/062-the-diff-sdiff-command.md new file mode 100755 index 0000000..8c886c1 --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/062-the-diff-sdiff-command.md @@ -0,0 +1,48 @@ + +# The `diff/sdiff` command +This command is used to display the differences in the files by comparing the files line by line. +### Syntax: + +``` +diff [options] File1 File2 +``` + +### Example + +1. Lets say we have two files with names a.txt and b.txt containing 5 Indian states as follows-: +``` +$ cat a.txt +Gujarat +Uttar Pradesh +Kolkata +Bihar +Jammu and Kashmir + +$ cat b.txt +Tamil Nadu +Gujarat +Andhra Pradesh +Bihar +Uttar pradesh + +``` +On typing the diff command we will get below output. +``` +$ diff a.txt b.txt +0a1 +> Tamil Nadu +2,3c3 +< Uttar Pradesh + Andhra Pradesh +5c5 + Uttar pradesh +``` + +### Flags and their Functionalities + +|**Short Flag** |**Description** | +|--|--| +| `-c`|To view differences in context mode, use the -c option. | +| `-u`|To view differences in unified mode, use the -u option. It is similar to context mode | +|`-i`|By default this command is case sensitive. To make this command case in-sensitive use -i option with diff. | +|`-version`|This option is used to display the version of diff which is currently running on your system. | diff --git a/docs/Linux-Commands/Working-With-Files/100-the-vim-command.md b/docs/Linux-Commands/Working-With-Files/100-the-vim-command.md new file mode 100755 index 0000000..3aaed71 --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/100-the-vim-command.md @@ -0,0 +1,106 @@ +# The `vim` command + +The [vim](https://www.vim.org/) is a text editor for Unix that comes with Linux, BSD, and macOS. It is known to be fast and powerful, partly because it is a small program that can run in a terminal (although it has a graphical interface). +Vim text editor is developed by [Bram Moolenaar](https://en.wikipedia.org/wiki/Bram_Moolenaar). It supports most file types and the vim editor is also known as a programmer's editor. It is mainly because it can be managed entirely without menus or a mouse with a keyboard. + +**Note:** Do not confuse `vim` with `vi`. `vi`, which stands for "Visual", is a text editor that was developed by [Bill Joy](https://en.wikipedia.org/wiki/Bill_Joy) in 1976. `vim` stands for "Vi Improved", and is an improved clone of the `vi` editor. + +### The most searched question about ```vim``` : +``How to exit vim editor?`` + +The most searched question about vim editor looks very funny but it's true that the new user gets stuck at the very beginning when using vim editor. + +The command to save the file and exit vim editor: ```:wq``` + +The command to exit vim editor without saving the file: ```:q!``` + +#### Fun reading: +Here's a [survey](https://stackoverflow.blog/2017/05/23/stack-overflow-helping-one-million-developers-exit-vim/) for the same question, look at this and do not think to quit the vim editor. + +### Installation: +First check if vim is already installed or not, enter the following command: +``` +vim --version +``` +If it is already installed it will show its version, else we can run the below commands for the installations: + +On Ubuntu/Debian: + +``` +sudo apt-get install vim +``` + +On CentOS/Fedora: + +``` +sudo yum install vim +``` +If you want to use advanced features on CentOS/Fedora, you'll need to install enhanced vim editor, to do this run the following command: + +``` +sudo yum install -y vim-enhanced +``` + +### Syntax: + +``` +vim [FILE_PATH/FILE_NAME] +``` + +### Examples: + +1. To open the file named "demo.txt" from your current directory: + +``` +vim demo.txt +``` + +2. To open the file in a specific directory: + +``` +vim {File_Path/filename} +``` + +3. To open the file starting on a specific line in the file: + +``` +vim {File_Path/filename} +LINE_NUMBER +``` +### Modes in vim editor: +There are some arguments as to how many modes that vim has, but the modes you're most likely to use are ```command mode``` and ```insert mode```. These [modes](https://www.freecodecamp.org/news/vim-editor-modes-explained/) will allow you to do just about anything you need, including creating your document, saving your document, and doing advanced editing, including taking advantage of search and replace functions. + +### Workflow of `vim` editor: +1. Open a new or existing file with ```vim filename```. +2. Type ```i``` to switch into insert mode so that you can start editing the file. +3. Enter or modify the text of your file. +4. When you're done, press the ```Esc``` key to exit insert mode and back to command mode. +5. Type :w or :wq to save the file or save and exit from the file respectively. + +### Interactive training + +In this interactive tutorial, you will learn the different ways to use the `vim` command: + +[The Open vim Tutorial](https://www.openvim.com/) + +### Additional Flags and their Functionalities: + +|**Flags/Options** |
**Description**
| +|:---|:---| +|`-e`|Start in Ex mode (see [Ex-mode](http://vimdoc.sourceforge.net/htmldoc/intro.html#Ex-mode))| +|`-R`|Start in read-only mode| +|`-R`|Start in read-only mode| +|`-g`|Start the [GUI](http://vimdoc.sourceforge.net/htmldoc/gui.html#GUI)| +|`-eg`|Start the GUI in Ex mode| +|`-Z`|Like "vim", but in restricted mode| +|`-d`|Start in diff mode [diff-mode](http://vimdoc.sourceforge.net/htmldoc/diff.html#diff-mode)| +|`-h`|Give usage (help) message and exit| +|`+NUMBER`|Open a file and place the cursor on the line number specified by NUMBER| + +### Read more about vim: + +vim can not be learned in a single day, use in day-to-day tasks to get hands-on in vim editor. + +To learn more about ```vim``` follow the given article: + +[Article By Daniel Miessler](https://danielmiessler.com/study/vim/) + diff --git a/docs/Linux-Commands/Working-With-Files/102-the-find-command.md b/docs/Linux-Commands/Working-With-Files/102-the-find-command.md new file mode 100755 index 0000000..1a0f80c --- /dev/null +++ b/docs/Linux-Commands/Working-With-Files/102-the-find-command.md @@ -0,0 +1,70 @@ +# The `find` command + +The `find` command lets you **search for files in a directory hierarchy** + +- Search a file with specific name. +- Search a file with pattern +- Search for empty files and directories. + + +### Examples: + +1. Search a file with specific name: + +```[linux] +find ./directory1 -name sample.txt +``` + +2. Search a file with pattern: + +```[linux] +find ./directory1 -name '*.txt' +``` + +3. To find all directories whose name is test in / directory. + +```[linux] +find / -type d -name test +``` + +4. Searching empty files in current directory + +```[linux] +find . -size 0k +``` + +### Syntax: + +```[linux] +find [options] [paths] [expression] +``` +**In Simple words** +```[linux] +find [where to start searching from] + [expression determines what to find] [-options] [what to find] +``` + +### Additional Flags and their Functionalities: + +Commonly-used primaries include: +- `name` pattern - tests whether the file name matches the shell-glob pattern given. +- `type` type - tests whether the file is a given type. Unix file types accepted include: + +| **options** | **Description** | +| :------------- | :-------------------------------------------------------------------------------------------------------- | +| `b` | block device (buffered) | +| `d` | directory | +| `f` | regular file | +| `l` | Symbolic link | +| `-print` | always returns true; prints the name of the current file plus a newline to the stdout. | +| `-mtime n` | find's all the files which are modified n days back. | +| `-atime n` | find's all the files which are accessed 50 days back. | +| `-cmin n` | find's all the files which are modified in the last 1 hour.| +| ` -newer file` | find's file was modified more recently than file.| +| `-size n` | File uses n units of space, rounding up.| + +### Help Command +Run below command to view the complete guide to `find` command or [click here](https://en.wikipedia.org/wiki/Find_(Unix)). +```[linux] +man find +``` diff --git a/docs/Linux-Commands/index.md b/docs/Linux-Commands/index.md new file mode 100755 index 0000000..c57a486 --- /dev/null +++ b/docs/Linux-Commands/index.md @@ -0,0 +1,15 @@ +# Linux Commands Home + +You wanna manage Linux servers, right? You wanna stop wasting time wading through endless command lists? + +**Here's the truth:** You're drowning in noise. Hundreds of Linux commands? Who cares? You think Fortune 500 companies and the US government need *all* of them? They don't. I've managed their servers. And I've done it with a fraction of those commands. + +**Here's the deal:** I've stripped away the fluff. I've distilled the chaos. What's left? The 50 commands I *actually* use. The 50 commands that get the job done. + +**Why 50?** Because that's all you need. That's all *I* need. And if it's good enough for me, it's damn sure good enough for you. + +**Time is your most valuable asset.** You're not here to memorize every obscure Linux command. You're here to build, to scale, to dominate. You're here to *win*. + +**Learn the 50 commands that actually matter.** Get the system that cuts through the noise. Get the training that delivers results. This isn't theory. This is what I use. This is what *works*. + +**Good enough for SoftwareShinobi, good enough for you.** diff --git a/docs/Proving-Grounds/Resources/help.md b/docs/Proving-Grounds/Resources/help.md new file mode 100755 index 0000000..b277446 --- /dev/null +++ b/docs/Proving-Grounds/Resources/help.md @@ -0,0 +1,3 @@ +# help + +`Note for VMs`: You may fail to connect to overthewire.org via SSH with a 'broken pipe error' when the network adapter for the VM is configured to use NAT mode. Adding the setting IPQoS throughput to /etc/ssh/ssh_config should resolve the issue. If this does not solve your issue, the only option then is to change the adapter to Bridged mode. diff --git a/docs/Proving-Grounds/Resources/tips.md b/docs/Proving-Grounds/Resources/tips.md new file mode 100755 index 0000000..4c7410c --- /dev/null +++ b/docs/Proving-Grounds/Resources/tips.md @@ -0,0 +1,17 @@ +# Pro Tips + +There are several things you can try when you are unsure how to continue: + +* First, if you know a command, but don’t know how to use it, try the manual (man page) by entering man . For example, man ls to learn about the "ls" command. The "man" command also has a manual, try it! When using man, press q to quit (you can also use / and n and N to search). + +* Second, if there is no man page, the command might be a shell built-in. In that case use the "help " command. E.g. help cd + +* Also, your favorite search-engine is your friend. Learn how to use it! I recommend Google. + +* Lastly, if you are still stuck, you can join us via chat + +## What To Do When Lost + +You will encounter many situations in which you have no idea what you are supposed to do. Don’t panic! Don’t give up! The purpose of this game is for you to learn the basics. + +Part of learning the basics, is reading a lot of new information. If you’ve never used the command line before, a good first read is this introduction to user commands. diff --git a/docs/Proving-Grounds/index.md b/docs/Proving-Grounds/index.md new file mode 100755 index 0000000..115ee08 --- /dev/null +++ b/docs/Proving-Grounds/index.md @@ -0,0 +1,17 @@ +# Home + +The linux war game help you to learn and practice security concepts in the form of fun-filled games. + +Presented to you by Software Shinobi and the team over at Valorant Digital. + +To find out more about a certain wargame, just visit its page linked from the menu on the left. + +Otherwise, click a war game and get to work. + +``` +Team Six: The Monaco Heist (/The-Monaco-Heist) + +Team Six: Infiltrating Machine City (Coming Soon) + +… +``` diff --git a/docs/assets/cover.jpg b/docs/assets/cover.jpg new file mode 100755 index 0000000..d6db238 Binary files /dev/null and b/docs/assets/cover.jpg differ diff --git a/docs/assets/cover.jpg-bak b/docs/assets/cover.jpg-bak new file mode 100755 index 0000000..f428793 Binary files /dev/null and b/docs/assets/cover.jpg-bak differ diff --git a/docs/assets/cover.png b/docs/assets/cover.png new file mode 100755 index 0000000..117eeb4 Binary files /dev/null and b/docs/assets/cover.png differ diff --git a/docs/assets/styling (copy 1).css b/docs/assets/styling (copy 1).css new file mode 100755 index 0000000..191b65f --- /dev/null +++ b/docs/assets/styling (copy 1).css @@ -0,0 +1,49 @@ +ul.nav.navbar-nav.ml-auto { + + background: purple; + + display: none; + +} + +div p a { + background: #FF4742; + border: 1px solid #FF4742; + border-radius: 6px; + box-shadow: rgba(0, 0, 0, 0.1) 1px 2px 4px; + box-sizing: border-box; + color: #FFFFFF; + cursor: pointer; + display: inline-block; + font-family: nunito,roboto,proxima-nova,"proxima nova",sans-serif; + font-size: 16px; + font-weight: 800; + line-height: 16px; + min-height: 40px; + outline: 0; + padding: 12px 14px; + text-align: center; + text-rendering: geometricprecision; + text-transform: none; + user-select: none; + -webkit-user-select: none; + touch-action: manipulation; + vertical-align: middle; +} + +p a:hover, +p a:active { + + background-color: initial; + + background-position: 0 0; + + color: #FF4742; + +} + +p a:active { + + opacity: .5; + +} diff --git a/docs/assets/styling (copy 2).css b/docs/assets/styling (copy 2).css new file mode 100755 index 0000000..9227bbc --- /dev/null +++ b/docs/assets/styling (copy 2).css @@ -0,0 +1,16 @@ +body p { + + font-size: 0.9rem; + + line-height: 1.5; + +} + + +body a { + + font-size: 0.85rem; + + line-height: 1.5; + +} diff --git a/docs/assets/styling.css b/docs/assets/styling.css new file mode 100755 index 0000000..d2e8c9f --- /dev/null +++ b/docs/assets/styling.css @@ -0,0 +1,16 @@ +body p { + + font-size: 0.9rem; + + line-height: 1.5; + +} + + +body { + + font-size: 0.85rem; + + line-height: 1.5; + +} diff --git a/docs/connect.md b/docs/connect.md new file mode 100755 index 0000000..668f801 --- /dev/null +++ b/docs/connect.md @@ -0,0 +1,49 @@ +# Connect To The Server + +A Linux Learning Playground Situation presented by Software Shinobi. + +!["Shinobi Academy Linux"](/cover.png) + +wanna play with the application in this picture? connect to the server using the instructions below and run the command `hollywood` + +## Introduction: + +Welcome, aspiring Linux ninjas! This tutorial will guide you through accessing Shinobi Academy Linux, a custom-built server designed to provide a safe and engaging environment for you to learn and experiment with Linux. + +## What You'll Learn: + +* Connecting to a Linux server (using SSH) +* Basic Linux commands (navigation, listing files, etc.) +* Exploring pre-installed tools like cmatrix and hollywood + +## What You'll Need: + +* A computer with internet access +* An SSH client (built-in on most Linux and macOS systems, downloadable for Windows) + +## About Shinobi Academy: + +Shinobi Academy, the online learning platform brought to you by Softwareshinobi! + +Designed to empower aspiring tech enthusiasts, Shinobi Academy offers a comprehensive range of courses and resources to equip you with the skills you need to excel in the ever-evolving world of technology. + +## Connecting to Shinobi Academy Linux: + +1. Open your SSH client. +2. Enter the following command (including the port number): + +``` +ssh -p 2222 shinobi@linux.softwareshinobi.com +``` + +3. When prompted, enter the password "shinobi". + +``` +username / shinobi +``` + +``` +password / shinobi +``` + +**Congratulations!** You're now connected to Shinobi Academy Linux server. diff --git a/docs/cover.png b/docs/cover.png new file mode 100755 index 0000000..0ec8dfd Binary files /dev/null and b/docs/cover.png differ diff --git a/docs/index.md b/docs/index.md new file mode 100755 index 0000000..4c77f22 --- /dev/null +++ b/docs/index.md @@ -0,0 +1,41 @@ +# Home + +A Linux Learning Playground Situation presented by Software Shinobi. + +!["Shinobi Academy Linux"](/cover.png) + +wanna play with the application in this picture? connect to the server using the instructions below and run the command `hollywood` + +## Introduction: + +Welcome, aspiring Linux ninjas! + +This tutorial will guide you through accessing Shinobi Academy Linux, a custom-built server designed to provide a safe and engaging environment for you to learn and experiment with Linux. + +Brought to you by Softwareshinobi ([https://softwareshinobi.com/](https://softwareshinobi.com/)). + +This server is your gateway to the exciting world of open-source exploration. + +**Experimenting with these tools is a great way to explore the possibilities of Linux.** + +## Learn Linux Commands: + +I've managed servers for Fortune 500 companies and the US government. + +There are hundreds of linux commands. + +But I've wittled all the hundreds commands down to the ~50 the I personally know. + +You won't need more than these 50 commands to manage linux servers. + +Good enough for SoftwareShinobi, good enough for you. + +**Learn The Essential Linux Commands** [Click Here](/Linux-Commands) + +## Connect To The Server: + +Get connected to the FREE public ubuntu linux server. + +Use the connection details below: + +**Connect To The Server** [Learn More!](/connect) diff --git a/docs/training.md b/docs/training.md new file mode 100755 index 0000000..ae48f2d --- /dev/null +++ b/docs/training.md @@ -0,0 +1,12 @@ +# Private Training w/ Me + +Master Linux Like a Pro: 1-on-1 Tutoring: + +**Tired of fumbling in the terminal?** Imagine wielding Linux commands with ease, managing servers like a corporate ninja – just like my government and corporate gigs. + +**1-on-1 tutoring unlocks your potential:** + +* **Terminal mastery:** Conquer the command line and automate tasks like a pro. +* **Become a command jedi:** Craft commands with lightning speed, streamlining your workflow. + +**Ready to transform your skills?** [Learn More!](https://training.softwareshinobi.com/linux) diff --git a/mkdocs.bash b/mkdocs.bash new file mode 100755 index 0000000..ebcd21b --- /dev/null +++ b/mkdocs.bash @@ -0,0 +1 @@ +reset;clear;mkdocs serve diff --git a/mkdocs.yml b/mkdocs.yml new file mode 100644 index 0000000..1c5ebb0 --- /dev/null +++ b/mkdocs.yml @@ -0,0 +1,39 @@ + +docs_dir: docs + +site_name: "Java Team Six: Docker" + +theme: + + palette: + + scheme: slate + + primary: deep orange + + accent: purple + + ## + ## Find More Themes Here: + ## + ## https://mkdocs.github.io/mkdocs-bootswatch/ + ## + ## List of theme values: + ## + ## mkdocs, readthedocs, material, cerulean, cosmo, + ## cyborg, darkly, flatly, journal, litera, lumen, lux, + ## materia, minty, pulse, sandstone, simplex, slate, solar, + ## spacelab, superhero, united, yeti + ## + + name: material + + ## + ## you can alternate colors for the navigation header. + ## + ## Allowed values: primary (the default), dark, and light: + ## + + nav_style: primary + +extra_css: [assets/styling.css] diff --git a/provision.bash b/provision.bash new file mode 100755 index 0000000..48612f9 --- /dev/null +++ b/provision.bash @@ -0,0 +1,15 @@ +#!/bin/bash + +set -e + +set -x + +## + +apt update + +## + +apt install pip -y + +pip install mkdocs-material --break-system-packages