How to use Conditional Statements on Bash Script (if, elif)

To Use Conditional Statements On Bash Script (if, elif)

Introduction

Conditional statements define “if a condition is true, then do that, otherwise do this instead.” Bash conditionals let you write code that performs different tasks based on specified checks. These checks can be based on a simple assessment that results in a true or false result.

Procedure

Step 1: Check the OS version by using the below command

globalt@linuxhelp:~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 22.04.3 LTS
Release:	22.04
Codename:	jammy

Step 2: Create a file by using your favourite editor, here I’m using vim editor

globalt@linuxhelp:~$ vim if.sh
Copy the following lines to the file
#!/bin/bash
if [ $UID -eq 0 ]
then
echo "You are root"
fi

Step 3: Give execute permission to the user by using the below command

globalt@linuxhelp:~$ chmod +x if.sh

Step 4: Now run the script from the globalt user by using the below command

globalt@linuxhelp:~$ ./if.sh
There is no output

Step 5: Switch to the root user by using the below command

globalt@linuxhelp:~$ su root
Password:

userroot@linuxhelp:/home/globalt# ./if.sh
You are root

root@linuxhelp:/home/globalt# exit
exit

globalt@linuxhelp:~$ vim if.sh
Copy the following lines to the file
if [ $UID -eq 0 ]
then
        echo "You are root"
else
        echo "You are not root user"
fi

globalt@linuxhelp:~$ ./if.sh
You are not root user

globalt@linuxhelp:~$ vim if.sh
Copy the following lines to the file
if [ $UID -eq 0 ]
then
        echo "You are root"
elif [ $UID -eq 1000 ]
then
        echo "You are globalt user"
else
        echo "You are not root user"
fi

globalt@linuxhelp:~$ ./if.sh
You are globalt user