Day45-Shell-Scripting-Basics.md

Day 45 of Cisco Linux Essentials Course

Covered Shell Scripting basics today — and passed Chapter 11 and Chapter 12 exams both with 80%.

Why Shell Scripting Matters

Every sysadmin/DevOps engineer needs this skill. Tasks that would take hours to complete manually, one command at a time, can be done in minutes with a script.

In simple terms: Shell scripting is taking your repetitive daily commands, saving them into a text file, and having them execute line by line automatically.

Two Ways to Execute a Script

Method 1:

sh test.sh
bash test.sh

Doesn't require the script file to have execute permission.

Method 2:

./test.sh

Running it directly like this requires the file to have execute permission set first (chmod +x test.sh).

The Shebang (#!)

The very first line of a script defines the interpreter:

#!/bin/bash

This tells the operating system exactly which shell should process the commands inside the file.

Scripting's Three Fundamental Pillars

For real automation, three building blocks come together:

• Variables — for storing temporary information/data
• Conditionals (if/else) — for logical decision-making
• Loops — for repeating a task's execution

What's Next

6 chapters left in the course — wrapping it up to get the certification, then moving into KodeKloud for deeper hands-on, practical labs.

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