122 lines
1.9 KiB
Markdown
122 lines
1.9 KiB
Markdown
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# Variables
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Like any language, Bash uses variables. No strict data types here; a variable holds numbers or characters.
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Assign a value:
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```bash
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name="Shinobi"
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```
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> **Note:** No spaces around the `=` sign. This is critical.
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Access the value using `$` before the variable name:
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```bash
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echo $name
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```
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While optional, wrapping the name in curly braces is good practice for clarity:
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```bash
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echo ${name}
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```
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Both would output: `Shinobi`.
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Now, let's build a script.
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First, create the file:
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```bash
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touch shinobi.sh
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```
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Then, open `shinobi.sh` and add this content to include a variable:
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```bash
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#!/usr/bin/env bash
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name="Shinobi"
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echo "Hi there $name"
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```
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Save and exit.
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Make it executable:
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```bash
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chmod +x shinobi.sh
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```
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Run your script:
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```bash
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./shinobi.sh
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```
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You'll see:
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```bash
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Hi there Shinobi
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```
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This script:
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* `#!/usr/bin/env bash`: Sets the interpreter.
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* `name="Shinobi"`: Defines `name` with its value.
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* `echo "Hi there $name"`: Outputs the welcome message using the variable.
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You can use multiple variables:
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```bash
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#!/usr/bin/env bash
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name="Shinobi"
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greeting="Hello"
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echo "$greeting $name"
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```
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Save and run `shinobi.sh` again:
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```bash
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./shinobi.sh
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```
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Output:
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```bash
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Hello Shinobi
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```
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No semicolons needed at line ends.
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### Command Line Parameters
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Bash scripts also read variables passed directly from the command line. These are called parameters.
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Run your script with inputs like this:
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```bash
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./shinobi.sh Troy buddy!
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```
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Now, modify your `shinobi.sh` file to access these parameters:
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```bash
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#!/usr/bin/env bash
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echo "Hello there" $1 # $1: first parameter
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echo "Hello there" $2 # $2: second parameter
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echo "Hello there" $@ # $@: all parameters
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```
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The output for `./shinobi.sh Troy buddy!` will be:
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```bash
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Hello there Troy
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Hello there buddy!
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Hello there Troy buddy!
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```
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