In Linux, scripting is an essential skill for automating repetitive tasks, system administration, and cybersecurity. Writing shell scripts allows you to automate tasks like backups, process management, monitoring system health, and more. In this section, we’ll focus on writing basic shell scripts using Bash, the most common shell in Linux systems.

What is a Shell Script?

A shell script is a file containing a series of commands that the shell (usually Bash) will execute. It allows you to automate tasks that you would normally perform manually on the command line.

• Shebang (#!): The first line of a script specifies the interpreter that should be used to execute the script. For example, #!/bin/bash tells the system to use Bash for executing the script.
• Bash Commands: These are the commands and logic written in the script. They can include basic shell commands, loops, conditionals, and function definitions.

Basic Script Syntax

A simple Bash script looks like this:

#!/bin/bash
# This is a comment, it won't be executed

echo "Hello, World!"

• #!/bin/bash: This is the shebang, which tells the system to use the Bash shell to interpret the script.
• echo: The echo command outputs text to the terminal.
• Comments: Anything after the # is considered a comment and won't be executed.

Creating Your First Script

• Create a new script file: Use any text editor to create a script file, such as nano, vim, or gedit: nano hello_world.sh
• Write the script:

#!/bin/bash
echo "Hello, World!"

• Save and exit: In nano, press Ctrl + X, then press Y to confirm saving, and press Enter to save the file.
• Make the script executable: Use the chmod command to make your script executable: chmod +x hello_world.sh
• Run the script: Now, you can run the script: ./hello_world.sh
• Output:

Hello, World!