How to Create and Run Executable Bash Scripts on Linux

Creating a Bash script file

Create a new file with the .sh extension using the touch command.

touch hello_script.sh

Writing the script

Open the file with vim (or any editor) and insert a shebang line followed by a simple command, for example:

#!/bin/bash
echo "Hello World"

Save the file and exit the editor.

Running the script

There are two ways to execute the script. The first uses the sh or bash interpreter explicitly:

sh hello_script.sh
bash hello_script.sh

Both commands output Hello World.

Setting execute permission

Make the script directly runnable by adding the executable flag with chmod:

chmod +x hello_script.sh

Running the script directly

After the permission is set, run the script without specifying the interpreter:

./hello_script.sh

Backup script example

A more practical example creates a backup script that archives /var/log into a timestamped tar.gz file.

#!/bin/bash
TIME=`date +%Y_%m_%d`
DESTINATION=/tmp/backup-$TIME.tar.gz
SOURCE=/var/log
tar -zcvf $DESTINATION $SOURCE

Give the script execute permission and run it:

chmod +x backup_script.sh
./backup_script.sh

The command produces a compressed backup file in /tmp named with the current date.