Day 8 of 90DaysOfDevOps : Shell Scripting Challenge🐧

Task 1: Adding Comments in Bash Scripts 📝

Comments are notes added in code to explain what each part does, making it easier for others (and yourself) to understand later. Comments in bash scripts start with a #.

#!/bin/bash
# This script greets the user
echo "Hello, user!"

In the above script:

• # This script greets the user is a comment and won’t be executed.

• The echo command will display "Hello, user!"

---

Task 2: Displaying Messages with echo 💬

The echo command is used to print text to the terminal. This is great for providing messages, displaying results, or debugging.

#!/bin/bash
echo "Welcome to Bash scripting!"

When you run this script, you’ll see:

Welcome to Bash scripting!

---

Task 3: Using Variables 📦

Variables store data like numbers, text, or filenames. You can create a variable by assigning it a value, which can then be referenced in the script.

#!/bin/bash
greeting="Hello"
name="Pooja"
echo "$greeting, $name!"

Output:

Hello, Pooja!

---

Task 4: Using Variables for Simple Math ➕

You can use variables to perform calculations in a script. In this example, we’ll create a script that takes two numbers and prints their sum.

#!/bin/bash
num1=10
num2=20
sum=$((num1 + num2))
echo "The sum of $num1 and $num2 is $sum"

Output:

The sum of 10 and 20 is 30

---

Task 5: Built-in Variables for Useful Information 🔍

Bash has built-in variables that hold useful system information. Here are three common ones:

• $USER: The current username.

• $HOME: The path to the current user’s home directory.

• $PWD: The current working directory.

#!/bin/bash
echo "User: $USER"
echo "Home Directory: $HOME"
echo "Current Directory: $PWD"

Output:

User: pooja
Home Directory: /home/pooja
Current Directory: /home/pooja/scripts

---

Task 6: Using Wildcards for Pattern Matching 🌟

Wildcards are special characters like * used to match patterns in filenames. For example, to list all .txt files in a directory, we can use * to match any file ending in .txt.

#!/bin/bash
echo "Listing all .txt files in the directory:"
ls *.txt

If there are files like notes.txt and data.txt in the directory, the output will be:

Listing all .txt files in the directory:
notes.txt
data.txt

---

Summary 📝

Bash scripting lets you automate tasks efficiently. By mastering comments, echo, variables, built-in variables, and wildcards, you can start building useful scripts to make your work easier!