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Introduction to Bash Commands and Scripting

By Abdul Muiz

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What is Bash?

Bash (short for Bourne Again SHell) is a command-line interpreter that allows you to interact directly with your computer’s operating system.
Using Bash, you can manage files, automate tasks, and build powerful workflows — all by typing simple text commands.
Learning Bash is a rite of passage for anyone serious about mastering Unix-like systems.

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Essential Bash Commands

The following commands form the foundation of working in a Bash environment.

File and Directory Management

Command	Description	Example
pwd	Display the current working directory	pwd
ls	List files and directories	ls -l
cd	Change directory	cd ~/Documents
mkdir	Create a new directory	mkdir NewFolder
touch	Create a new, empty file	touch notes.txt
cp	Copy files or directories	cp source.txt destination.txt
mv	Move or rename files or directories	mv oldname.txt newname.txt
rm	Remove files	rm file.txt
rmdir	Remove empty directories	rmdir EmptyFolder

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Clearing the Terminal

You can clear the terminal screen using:

clear

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Editing Files with Vim

Vim is a powerful text editor built directly into the terminal. To create or edit a file:

vim myfile.sh

Basic Vim commands:

• Press i to enter Insert mode (start typing).
• Press Esc to exit Insert mode.
• Type :w to save the file.
• Type :q to quit Vim.
• Type :wq to save and quit in one step.

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Writing Your First Bash Script

Step 1: Create a Script File

Open a new file using Vim:

vim myscript.sh

Inside, write the following:

#!/bin/bash
echo "Hello, world! Welcome to Bash scripting."

The first line (#!/bin/bash) is called the shebang — it tells the system to use Bash to run the script.

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Step 2: Make the Script Executable

Before running the script, you need to make it executable:

chmod +x myscript.sh

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Step 3: Run the Script

Execute your script:

./myscript.sh

You should see:

Hello, world! Welcome to Bash scripting.

Congratulations — you have written and executed your first Bash script.

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Key Concepts in Bash Scripting

Concept	Description
#	A comment. Used to explain your code.
echo	Prints text to the terminal.
read	Takes input from the user.
Variables ($VAR)	Store and reuse data.
if, then, else, fi	Conditional logic (decisions).
for, while, do, done	Loops (repeat actions).

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Simple Script Examples

Greeting the User

#!/bin/bash

echo "Enter your name:"
read username
echo "Welcome, $username!"

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Basic If-Else Example

#!/bin/bash

echo "Enter a number:"
read number

if [ $number -gt 10 ]; then
    echo "The number is greater than 10."
else
    echo "The number is 10 or less."
fi

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Loop Example

#!/bin/bash

for i in {1..5}
do
    echo "Iteration number $i"
done

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Useful Bash Shortcuts

• && → Run the next command only if the first one succeeds:

  mkdir TestFolder && cd TestFolder

• || → Run the next command only if the first one fails:

  cd Nonexistent || echo "Directory does not exist."

• ; → Run multiple commands sequentially:

  echo "First command"; echo "Second command"

• $(...) → Capture the output of a command:

  echo "Today is $(date)"

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Final Thoughts

Learning Bash is more than learning a set of commands — it is about thinking systematically and automating your work.
It turns the computer from a passive machine into a powerful tool that bends to your will.

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