How to get a variable value from the source file in Bash Script on Debian 12

To Get Variable Value From The Source File In Bash Script On Debian 12

In Bash scripting on Debian 12, obtaining variable values from a source file is a key technique for managing configuration settings or external parameters. This process involves integrating external files into scripts, enabling the script to access and utilize predefined variables.

Procedure Steps:

Step 1: Check the OS version by using following command.

root@linuxhelp:~/linuxhelp# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
NAME="Debian GNU/Linux"
VERSION_ID="12"
VERSION="12 (bookworm)"
VERSION_CODENAME=bookworm
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL=https://bugs.debian.org/

Step 2: Create a script file to assign value for the variable by using following command.

root@linuxhelp:~/linuxhelp# vim value
#!/bin/bash
VAR=$(which pwd)

Step 3: Make the executable permission by using following command.

root@linuxhelp:~/linuxhelp# chmod +x value

Step 4: Long list the file to check executable permission by using following command.

root@linuxhelp:~/linuxhelp# ls -la
total 12
drwxr-xr-x 2 root root 4096 Dec  8 05:18 .
drwx------ 8 root root 4096 Dec  8 05:18 ..
-rwxr-xr-x 1 root root   30 Dec  8 05:18 value

Step 5: Create a script file to get variable value from source file by using following command.

root@linuxhelp:~/linuxhelp# vim variable
#!/bin/bash

source ./value

VAR1=$(which pwd)

if [ $VAR != $VAR1 ]
then
	echo "The variable values are same, so copy the variable output!"
	cp $VAR /root/linuxhelp/output
else
	echo "The variable values are not same!"
fi

root@linuxhelp:~/linuxhelp# chmod +x variable

root@linuxhelp:~/linuxhelp# ls -la
total 16
drwxr-xr-x 2 root root 4096 Dec  8 05:21 .
drwx------ 8 root root 4096 Dec  8 05:21 ..
-rwxr-xr-x 1 root root   30 Dec  8 05:18 value
-rwxr-xr-x 1 root root  222 Dec  8 05:21 variable

root@linuxhelp:~/linuxhelp# ./variable 
The variable values are same, so copy the variable output!

root@linuxhelp:~/linuxhelp# ls -la
total 60
drwxr-xr-x 2 root root  4096 Dec  8 05:24 .
drwx------ 8 root root  4096 Dec  8 05:23 ..
-rwxr-xr-x 1 root root 43952 Dec  8 05:24 output
-rwxr-xr-x 1 root root    30 Dec  8 05:18 value
-rwxr-xr-x 1 root root   222 Dec  8 05:23 variable

root@linuxhelp:~/linuxhelp# vim variable
#!/bin/bash

source ./value

VAR1=$(which pwd)

if [ $VAR != $VAR1 ]
then
	echo "The variable values are same, so copy the variable output!"
	cp $VAR /root/linuxhelp/output
else
	echo "The variable values are not same!"
	rm -rf /root/linuxhelp/output
fi

root@linuxhelp:~/linuxhelp# ./variable 
The variable values are not same!

root@linuxhelp:~/linuxhelp# ls -la
total 16
drwxr-xr-x 2 root root 4096 Dec  8 05:27 .
drwx------ 8 root root 4096 Dec  8 05:27 ..
-rwxr-xr-x 1 root root   30 Dec  8 05:18 value
-rwxr-xr-x 1 root root  254 Dec  8 05:27 variable