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Shell Scripting Tutorials for Beginners

Shell scripting takes the command line a step further by allowing you to automate repetitive tasks, create custom tools, and manage systems more efficiently. Instead of typing the same commands over and over, a shell script lets you bundle them together into a simple program that can run with a single command. Whether you’re managing files, monitoring processes, or deploying applications, shell scripting gives you the flexibility and control to get things done faster.

Pre-requisites

The per-requisites for learning shell scripting, especially if you’re a beginner are as follows:

Ubuntu tutorials on this website:

A Linux terminal is a text-based interface that allows you to interact with your Linux operating system by typing commands instead of using graphical menus and buttons.

 

Shell Scripting Tutorials for Beginners

What is Shell Scripting?

A shell script is a text file containing a sequence of commands that the Linux/Unix shell (like bash, sh, or zsh) can execute. It automates repetitive tasks, makes system administration easier, and can even build complete programs.

Getting Started

Hello World Script

Create a script file.

Let’s call it as “hello.sh”. Use the touch command to create the file.

$ touch hello.sh

Open Vim with a filename

Open the file using the vim editor. Use the following command.

$ vim hello.sh

Enter Insert Mode to write code

  • Press i to enter insert mode.

  • Type your shell script code, for example:

 

#!/bin/bash
echo "Hello, World!"

Linux Shell Script Code

 

#!/bin/bash → Shebang line (tells system to use bash shell)

echo → Prints text on screen

Save the File

  • Press Esc to return to normal mode.

  • Type the following command and press Enter:

Save and Exit

  • To save changes and quit Vim:

  • :wq

Add Execute Permission

Issue the following command to give the execute permission to the script file.

$ chmod +x hello.sh

 

The chmod command in Linux is used to change file or directory permissions. It controls who can read (r), write (w), or execute (x) a file. Permissions can be set using symbolic mode (e.g., chmod u+x file.sh) or numeric mode (e.g., chmod 755 file.sh). This ensures secure access control for users, groups, and others.

More information on the command:

Run the script

Execute the script with the following command:

$ ./hello.sh

 

Basics of Shell Scripting

Variables

<em>#!/bin/bash
name="Alice"
echo "Hello $name"</em>

User Input

<em>#!/bin/bash
echo "Enter your name: "
read username
echo "Welcome, $username!"</em>

Conditional Statements

<em>#!/bin/bash
echo "Enter a number: "
read num
if [ $num -gt 10 ]; then
 echo "Number is greater than 10"
else
 echo "Number is 10 or less"
fi</em>

Loops

For Loop

<em>for i in 1 2 3 4 5
do
 echo "Number: $i"
done</em>

While Loop

<em>count=1
while [ $count -le 5 ]
do
 echo "Count = $count"
 ((count++))
done</em>

Functions

<em>#!/bin/bash
greet() {
 echo "Hello, $1"
}
greet "Naini"</em>

Command-line Arguments

In shell scripts, $1, $2, $3, … are called positional parameters. They represent the command line arguments (inputs) that are passed to the script when you run it.

  • $0 → The name of the script itself.

  • $1 → The first argument.

  • $2 → The second argument.

  • $3 → The third argument, and so on.

  • $# → The number of arguments passed.

  • $@ or $* → All arguments together.

Sample code

<em>#!/bin/bash
echo "Script name: $0"
echo "First argument: $1"
echo "Second argument: $2"
echo "All arguments: $@"</em>

Sample Run

./script.sh apple banana

Exit Status

<em>ls /notexist
echo "Exit status: $?"</em>