linux.softwareshinobi.com/landing/docs/Bash-Scripts/016-creating-an-interactive-menu-in-bash.md

Interactive Menu

Build interactive Bash menus. This guide shows you how to create a menu where users choose which actions to run, leveraging previously defined functions for server status checks:

• Memory usage
• CPU load
• TCP connections
• Kernel version

Here's the base script containing these functions:

#!/usr/bin/env bash

##
# Server status script:
#   - Memory usage
#   - CPU load
#   - Number of TCP connections
#   - Kernel version
##

server_name=$(hostname)

function memory_check() {
    echo ""
    echo "Memory usage on ${server_name}: "
    free -h
    echo ""
}

function cpu_check() {
    echo ""
    echo "CPU load on ${server_name}: "
    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}: "
    echo ""
    uname -r
    echo ""
}

function all_checks() {
    memory_check
    cpu_check
    tcp_check
    kernel_check
}

We'll now integrate this with a menu, allowing users to select a function to execute.

---

Add Color for Readability

Enhance your menu's readability with simple color functions. Add these variables and functions to your script:

##
# Color Variables
##
green='\e[32m'
blue='\e[34m'
red='\e[31m'
clear='\e[0m'

##
# Color Functions
##

ColorGreen(){
    echo -ne $green$1$clear
}
ColorBlue(){
    echo -ne $blue$1$clear
}
ColorRed(){
    echo -ne $red$1$clear
}

Use them like: $(ColorBlue 'Your text').

---

Build the Interactive Menu

Create a menu function containing the display logic, user input, and a case statement for selection.

menu(){
echo -ne "
My Server Status Menu
$(ColorGreen '1)') Memory usage
$(ColorGreen '2)') CPU load
$(ColorGreen '3)') TCP connections
$(ColorGreen '4)') Kernel version
$(ColorGreen '5)') Check All
$(ColorGreen '0)') Exit
$(ColorBlue 'Choose an option:') "
    read -r 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 $(ColorRed 'Invalid option.') ; menu ;;
    esac
}

Here's how it works:

• The echo -ne block prints the menu options, applying colors.
• read -r a captures user input into variable a.
• The case statement executes the corresponding function. After each function, menu is called again to display the menu for another choice, creating a loop. exit 0 handles the exit option.

Finally, call the menu function at the end of your script to start the interaction:

menu

---

Complete Script and Testing

Here's the entire script, menu.sh, combining all components:

#!/usr/bin/env 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}: "
    free -h
    echo ""
}

function cpu_check() {
    echo ""
    echo "CPU load on ${server_name}: "
    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}: "
    echo ""
    uname -r
    echo ""
}

function all_checks() {
    memory_check
    cpu_check
    tcp_check
    kernel_check
}

##
# Color Variables
##
green='\e[32m'
blue='\e[34m'
red='\e[31m'
clear='\e[0m'

##
# Color Functions
##

ColorGreen(){
    echo -ne $green$1$clear
}
ColorBlue(){
    echo -ne $blue$1$clear
}
ColorRed(){
    echo -ne $red$1$clear
}

menu(){
echo -ne "
My Server Status Menu
$(ColorGreen '1)') Memory usage
$(ColorGreen '2)') CPU load
$(ColorGreen '3)') TCP connections
$(ColorGreen '4)') Kernel version
$(ColorGreen '5)') Check All
$(ColorGreen '0)') Exit
$(ColorBlue 'Choose an option:') "
    read -r 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 $(ColorRed 'Invalid option.') ; menu ;;
    esac
}

# Call the menu function
menu

Save this code as menu.sh:

touch menu.sh

Open menu.sh and paste the script. Save and close. Then, make it executable and run:

chmod +x menu.sh
./menu.sh

You'll see the colored menu, prompting for input. Select an option (e.g., 1 for memory check), and the corresponding information will display before the menu reappears, ready for another choice.

---

Conclusion

You've built an interactive Bash menu, allowing users to effortlessly navigate script functionalities. This enhances user experience for your automation tools.

{notice} This content was inspired by a piece by softwareshinobi on Dev Team Six.