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docs/.Bash-Scripting/016-creating-an-interactive-menu-in-bash.md
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305
docs/.Bash-Scripting/016-creating-an-interactive-menu-in-bash.md
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# Creating an interactive menu in Bash
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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!
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We would reuse some of the code from the previous chapter, so if you have not read it yet make sure to do so.
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## Planning the functionality
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Let's start again by going over the main functionality of the script:
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* Checks the current Disk usage
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* Checks the current CPU usage
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* Checks the current RAM usage
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* Checks the check the exact Kernel version
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In case that you don't have it on hand, here is the script itself:
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```bash
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#!/bin/bash
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##
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# BASH menu script that checks:
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# - Memory usage
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# - CPU load
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# - Number of TCP connections
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# - Kernel version
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##
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server_name=$(hostname)
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function memory_check() {
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echo ""
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echo "Memory usage on ${server_name} is: "
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free -h
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echo ""
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}
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function cpu_check() {
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echo ""
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echo "CPU load on ${server_name} is: "
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echo ""
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uptime
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echo ""
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}
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function tcp_check() {
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echo ""
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echo "TCP connections on ${server_name}: "
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echo ""
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cat /proc/net/tcp | wc -l
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echo ""
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}
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function kernel_check() {
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echo ""
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echo "Kernel version on ${server_name} is: "
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echo ""
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uname -r
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echo ""
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}
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function all_checks() {
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memory_check
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cpu_check
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tcp_check
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kernel_check
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}
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```
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We will then build a menu that allows the user to choose which function to be executed.
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Of course, you can adjust the function or add new ones depending on your needs.
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## Adding some colors
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In order to make the menu a bit more 'readable' and easy to grasp at first glance, we will add some color functions.
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At the beginning of your script add the following color functions:
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```bash
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##
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# Color Variables
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##
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green='\e[32m'
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blue='\e[34m'
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clear='\e[0m'
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##
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# Color Functions
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##
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ColorGreen(){
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echo -ne $green$1$clear
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}
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ColorBlue(){
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echo -ne $blue$1$clear
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}
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```
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You can use the color functions as follows:
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```bash
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echo -ne $(ColorBlue 'Some text here')
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```
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The above would output the `Some text here` string and it would be blue!
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# Adding the menu
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Finally, to add our menu, we will create a separate function with a case switch for our menu options:
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```bash
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menu(){
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echo -ne "
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My First Menu
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$(ColorGreen '1)') Memory usage
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$(ColorGreen '2)') CPU load
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$(ColorGreen '3)') Number of TCP connections
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$(ColorGreen '4)') Kernel version
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$(ColorGreen '5)') Check All
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$(ColorGreen '0)') Exit
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$(ColorBlue 'Choose an option:') "
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read a
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case $a in
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1) memory_check ; menu ;;
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2) cpu_check ; menu ;;
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3) tcp_check ; menu ;;
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4) kernel_check ; menu ;;
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5) all_checks ; menu ;;
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0) exit 0 ;;
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*) echo -e $red"Wrong option."$clear; WrongCommand;;
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esac
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}
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```
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### A quick rundown of the code
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First we just echo out the menu options with some color:
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```
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echo -ne "
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My First Menu
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$(ColorGreen '1)') Memory usage
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$(ColorGreen '2)') CPU load
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$(ColorGreen '3)') Number of TCP connections
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$(ColorGreen '4)') Kernel version
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$(ColorGreen '5)') Check All
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$(ColorGreen '0)') Exit
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$(ColorBlue 'Choose an option:') "
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```
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Then we read the answer of the user and store it in a variable called `$a`:
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```bash
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read a
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```
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Finally, we have a switch case which triggers a different function depending on the value of `$a`:
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```bash
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case $a in
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1) memory_check ; menu ;;
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2) cpu_check ; menu ;;
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3) tcp_check ; menu ;;
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4) kernel_check ; menu ;;
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5) all_checks ; menu ;;
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0) exit 0 ;;
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*) echo -e $red"Wrong option."$clear; WrongCommand;;
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esac
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```
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At the end we need to call the menu function to actually print out the menu:
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```bash
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# Call the menu function
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menu
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```
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## Testing the script
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In the end, your script will look like this:
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```bash
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#!/bin/bash
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##
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# BASH menu script that checks:
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# - Memory usage
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# - CPU load
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# - Number of TCP connections
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# - Kernel version
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##
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server_name=$(hostname)
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function memory_check() {
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echo ""
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echo "Memory usage on ${server_name} is: "
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free -h
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echo ""
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}
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function cpu_check() {
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echo ""
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echo "CPU load on ${server_name} is: "
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echo ""
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uptime
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echo ""
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}
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function tcp_check() {
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echo ""
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echo "TCP connections on ${server_name}: "
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echo ""
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cat /proc/net/tcp | wc -l
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echo ""
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}
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function kernel_check() {
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echo ""
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echo "Kernel version on ${server_name} is: "
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echo ""
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uname -r
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echo ""
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}
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function all_checks() {
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memory_check
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cpu_check
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tcp_check
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kernel_check
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}
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##
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# Color Variables
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##
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green='\e[32m'
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blue='\e[34m'
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clear='\e[0m'
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##
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# Color Functions
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##
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ColorGreen(){
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echo -ne $green$1$clear
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}
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ColorBlue(){
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echo -ne $blue$1$clear
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}
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menu(){
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echo -ne "
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My First Menu
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$(ColorGreen '1)') Memory usage
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$(ColorGreen '2)') CPU load
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$(ColorGreen '3)') Number of TCP connections
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$(ColorGreen '4)') Kernel version
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$(ColorGreen '5)') Check All
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$(ColorGreen '0)') Exit
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$(ColorBlue 'Choose an option:') "
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read a
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case $a in
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1) memory_check ; menu ;;
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2) cpu_check ; menu ;;
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3) tcp_check ; menu ;;
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4) kernel_check ; menu ;;
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5) all_checks ; menu ;;
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0) exit 0 ;;
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*) echo -e $red"Wrong option."$clear; WrongCommand;;
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esac
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}
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# Call the menu function
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menu
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```
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To test the script, create a new filed with a `.sh` extension, for example: `menu.sh` and then run it:
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```bash
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bash menu.sh
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```
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The output that you would get will look like this:
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```bash
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My First Menu
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1) Memory usage
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2) CPU load
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3) Number of TCP connections
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4) Kernel version
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5) Check All
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0) Exit
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Choose an option:
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```
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You will be able to choose a different option from the list and each number will call a different function from the script:
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## Conclusion
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You now know how to create a Bash menu and implement it in your scripts so that users could select different values!
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>{notice} This content was initially posted on [DevDojo.com](https://devdojo.com/bobbyiliev/how-to-work-with-json-in-bash-using-jq)
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