Linux Bash Basics

What Is Bash?

Bash stands for:

Bourne Again Shell

It is a program that lets you control Linux by typing commands.

It is a shell, which means:

• It takes your typed commands
• Sends them to the operating system
• Shows you the results

You interact with Bash using a program called the Terminal.

Instead of clicking with a mouse, you type instructions.

Opening the Terminal

On most Linux systems:

• Press Ctrl + Alt + T
• OR
• Search for "Terminal" in the applications menu

You’ll see something like:

user@computer:~$

This is called the prompt.

• user = your username
• computer = your system name
• ~ = your home directory
• $ = regular user

If you see #, that means you are the root (administrator) user.

Understanding the Filesystem

Linux organizes files in a tree structure.

The top of the tree is:

/

This is called the root directory.

Important directories:

• /home → user files
• /etc → system configuration
• /bin → essential programs
• /usr → installed software

Your personal files are usually in:

/home/yourname

Shortcut:

~

means your home directory.

Basic Navigation Commands

Show Files

ls

List with details:

ls -l

List hidden files:

ls -a

Change Directory

cd foldername

Go back one level:

cd ..

Go to home directory:

cd ~

Go to root directory:

cd /

Creating and Deleting

Create a Folder

mkdir MyFolder

Remove a Folder

rmdir MyFolder

If the folder contains files:

rm -r MyFolder

Create a File

touch file.txt

Delete a File

rm file.txt

Viewing File Contents

Show file content:

cat file.txt

View long files page by page:

less file.txt

Copying and Moving Files

Copy a file:

cp file.txt backup.txt

Move or rename a file:

mv file.txt newname.txt

Permissions Basics

Linux uses read, write, and execute permissions.

View permissions:

ls -l

Change permissions:

chmod 755 file.txt

Running Programs

Run a program:

programname

Run a script:

bash script.sh

Make a script executable:

chmod +x script.sh
./script.sh

Getting Help

Most commands have built-in help.

man ls

Or shorter help:

ls --help

A Simple Practice Session

ls
mkdir TestFolder
cd TestFolder
touch hello.txt
ls
cat hello.txt
cd ..
rm -r TestFolder

What this does:

1. Lists files
2. Creates a folder
3. Enters the folder
4. Creates a file
5. Lists contents
6. Displays file content
7. Goes back
8. Deletes the folder

Important Concepts

1. Case Sensitivity

Linux IS case-sensitive.

These are different:

file.txt
File.txt
FILE.txt

2. Command Structure

Most Bash commands follow this pattern:

command [options] [target]

Example:

ls -l

• command = ls
• option = -l

3. Everything Is a File

In Linux:

• Regular files are files
• Folders are files
• Devices are files
• Processes are treated like files internally

This is a very important Linux concept.

ls
ls -l
ls -a

cd foldername
cd ..
cd ~
cd /

mkdir MyFolder
rmdir MyFolder
rm -r MyFolder

touch file.txt
rm file.txt

cat file.txt
less file.txt

cp file.txt backup.txt
mv file.txt newname.txt

ls -l
chmod 755 file.txt

programname
bash script.sh
chmod +x script.sh
./script.sh

man ls
ls --help

ls
mkdir TestFolder
cd TestFolder
touch hello.txt
ls
cat hello.txt
cd ..
rm -r TestFolder