DevOps & Linux Administration

Module V: Shell Scripting Basics. This module introduces shell scripting in Linux, including script creation, variables, user input, conditional statements, loops, and automation basics. Shell scripting is an essential skill in Linux administration, DevOps workflows, and server automation.

What is Shell Scripting?

A shell script is a file containing a sequence of Linux commands that are executed automatically by the shell. Instead of typing commands manually one by one, users can automate repetitive tasks using scripts.

Shell scripting is widely used for:

• Task automation
• System administration
• Server management
• Software deployment
• Backup and monitoring systems

Creating a Shell Script

Shell scripts are usually saved with the .sh extension. The first line of a script generally contains a special statement called the shebang.

#!/bin/bash

echo "Hello Linux"

echo "Welcome to Shell Scripting"

Executing a Shell Script

Before running a shell script, execute permission must be granted using the chmod command.

$ chmod +x script.sh

$ ./script.sh

Variables in Shell Scripting

Variables are used to store data values in shell scripts. Values can later be accessed and reused whenever required.

#!/bin/bash

name="Tanmay"

echo "Hello $name"

• Variables are assigned without spaces
• $ is used to access variable values
• Variables improve code reusability

Taking User Input

Shell scripts can accept input from users using the read command.

#!/bin/bash

echo "Enter your name"

read name

echo "Welcome $name"

Conditional Statements

Conditional statements allow scripts to make decisions based on conditions. The most commonly used conditional statement is if.

#!/bin/bash

num=10

if [ $num -gt 5 ]

then
  echo "Number is greater than 5"

fi

Loops in Shell Scripting

Loops are used to repeat a set of commands multiple times automatically.

#!/bin/bash

for i in 1 2 3 4 5

do
  echo $i

done

Automation using Shell Scripts

Shell scripting is extremely powerful for automating repetitive tasks. DevOps engineers use shell scripts for deployment, backups, monitoring, and server configuration.

Summary

In this chapter, we learned the fundamentals of shell scripting, including script creation, execution, variables, user input, conditional statements, loops, and automation basics. Shell scripting plays a major role in Linux administration and DevOps automation.