Day 27/ 30 Days of Linux Mastery: Introduction to Shell Scripting

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Introduction

Welcome back to Day 27 of this practical Linux challenge!

If you have been following my articles and practicing your commands on RHEL 9, then you are already using the shell!

Now, imagine having the shell perform multiple tasks for you automatically. That is what shell scripting is all about.

What is Shell Scripting?

A shell is a command-line interpreter that lets you interact with the operating system. Shell scripting is the process of writing a series of shell (command-line) instructions in a file that can be executed like a program.

Think of it like creating your own little tool to automate boring or repetitive tasks!

With it, you can:

Automate backups
Monitor system performance
Create users
Set scheduled tasks
Parse logs
Deploy services

Types of Shells

Linux systems support several types of shells. The most commonly used ones include:

Shell	Description
`sh`	The original Bourne shell. Simple, but limited.
`bash`	Bourne Again Shell – the most widely used and powerful shell on Linux (and the default on RHEL).
`zsh`	Z shell – known for features like auto-completion and customization.
`ksh`	Korn shell – used in enterprise environments.
`fish`	Friendly interactive shell – user-friendly and great for beginners.

For this tutorial, we will use bash, as it is the default on RHEL 9.

Real-World Scenario: Shell Scripting

Let's create and run our first shell script.

Open your terminal, create a file and this line into it

vim hello.sh   # note that script files end with a .sh

#!/bin/bash    # this is called shebang /bin/bash must always start the line in every script you are writing


echo "Hello, world! This is Amanda's first shell script in RHEL 9!"    # echo prints the message as an output on your terminal.

# Save and exit using:wq!

Now, give the script permission to run

chmod +x hello.sh     # this enables it to be executable

Verify the file has the execute permissions

ls -ltr hello.sh

Run the script on your terminal

./hello.sh

Conclusion

Shell scripting might sound scary at first, but once you try it, you will wonder why you didn’t start sooner. Even with just 3 commands, you can automate tasks that make your life easier.

In RHEL 9, this is one of the most useful beginner skills. Just remember: start simple, run often, and break things (on purpose lol).

See you in the next article, where we dive deeper into shell scripting!

If this is helpful to you, feel free to bookmark, comment, like and follow me for Day 28!

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I am always happy to learn and build with others in the tech space.

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