Introduction to Bash Scripting in Red Hat Linux

Welcome to Day 18 of the 30 Days of Linux Challenge!

Today’s milestone is a major step toward real-world automation and system control: Bash scripting.

Whether you’re managing servers, running tasks, or automating builds — Bash scripting is the backbone of Linux efficiency.

📚 Table of Contents

Why Bash Scripting Matters

Bash scripting allows you to:

• Automate repetitive manual work
• Create scheduled maintenance jobs
• Wrap complex Linux commands into one script
• Respond to system conditions dynamically

Instead of typing 5 commands every day — you can run one script and be done.

Your First Bash Script

Create the script
nano myfirstscript.sh

Add:

echo “Hello, world!”
date
whoami

Make it executable:

chmod +x myfirstscript.sh

./myfirstscript.sh

Working with Variables

myname=”CloudWhistler”
echo “Welcome, $myname!”

Notes:

• No spaces around =
• Use $variable to access

User Input in Scripts

echo “What is your name?”
read username
echo “Hello, $username!”

Conditional Logic (if-else)

read -p “Enter a number: ” num

if [ $num -gt 10 ]; then
echo “That’s a big number!”
else
echo “That’s a small number.”
fi

Common operators:

Operator Meaning
-eq Equal
-ne Not equal
-gt Greater than
-lt Less than
-ge Greater or equal
-le Less or equal

Loops: For and While

For Loop
for i in {1..5}
do
echo “Step $i”
done

While Loop

counter=1
while [ $counter -le 5 ]
do
echo “Count: $counter”
((counter++))
done

Functions in Bash

greet() {
echo “Hello, $1!”
}

greet “Linux”
greet “World”

Functions allow you to organize larger scripts into manageable blocks.

Try It Yourself

🧪 Practice ideas:

Ask the user for their name and greet them.

Create a loop that counts from 1 to 10.

Write a function that prints disk usage (df -h).

Combine conditionals + variables + user input.

Real-World Bash Script Examples

Why This Matters

Bash scripting is the gateway to serious automation in Linux.

✅ Speeds up your work
✅ Makes tasks repeatable and error-free
✅ Builds a foundation for tools like Ansible, Docker, Jenkins, and CI/CD pipelines