If you find yourself running the same sequence of Linux commands repeatedly, it is time to write a Bash script. Bash (Bourne Again Shell) is the default command-line interpreter for most Linux systems, and scripting allows you to automate complex tasks.

Creating Your First Script

A Bash script is simply a plain text file containing a list of commands.

1. Create a file: Create a new file, typically with a .sh extension (though the extension isn’t strictly necessary).

   touch myscript.sh

2. Add the Shebang: Open the file in an editor and add #!/bin/bash as the very first line. This tells the system to use the Bash interpreter to execute the file.
3. Write your commands: Add the commands you want to run.

   #!/bin/bash
   echo "Starting backup process..."
   tar -czf backup.tar.gz /home/user/documents
   echo "Backup complete!"

Making It Executable

Before you can run your script, you need to grant it execute permissions using the chmod command:

chmod +x myscript.sh

Now you can run it by specifying its path:

./myscript.sh

Variables and Control Structures

Bash scripting becomes powerful when you introduce variables and logic.

Variables:

#!/bin/bash
BACKUP_DIR="/var/backups"
echo "Saving to $BACKUP_DIR"

If/Else Statements:

#!/bin/bash
if [ -d "/var/www/html" ]; then
  echo "Web directory exists."
else
  echo "Web directory not found!"
fi

For Loops:

#!/bin/bash
for file in *.txt; do
  echo "Processing $file"
done

Starting with simple scripts and gradually adding logic is the best way to master Linux automation.