What Are Terminal Commands?

Terminal commands are text-based instructions. That allows you to communicate directly with your operating system. Instead of clicking icons or navigating through menus, you type commands to perform tasks. Such as creating files, managing folders, installing software, checking system information, and troubleshooting problems.

The Terminal is also known as:

• Terminal (Linux & macOS)
• Command Line Interface (CLI)
• Shell
• Console

Linux primarily uses shells like Bash and Zsh.

Example

Sposed that you’re the manager of a huge warehouse.

Using the graphical interface (GUI) is like walking to each shelf to find or organize products.

Using the Terminal is like giving instructions over a radio:

“Open Shelf A, move Box 5 to Shelf B, then count the remaining boxes.”

The workers immediately perform the task.

Similarly, when you type:

mkdir Projects

You’re telling Linux:

“Create a new folder named Projects.”

The operating system follows your instructions instantly.

Why Learn Terminal Commands?

Learning Terminal commands provides many benefits:

• Faster than using the mouse
• Better control over the operating system
• Essential for servers
• Required for cybersecurity
• Used by programmers
• Helpful for automation
• Useful for troubleshooting
• Required for cloud computing

Opening the Terminal

Most Linux distributions provide Terminal in the applications menu.

Shortcut:

Ctrl + Alt + T

Understanding the Command Structure

A command usually follows this format:

command [options] [arguments]

Example:

ls -l Documents

Where:

• ls → command
• -l → option
• Documents → argument

1. Check Current Directory

Command:

pwd

Output:

/home/student

Meaning:

Shows your current working directory.

Example:

Like checking your current location using Google Maps.

2. List Files

Command:

ls

Output:

Desktop

Downloads

Documents

Pictures

Useful options:

ls -l

Detailed list

ls -a

Shows hidden files

ls -lh

Human-readable file sizes

3. Change Directory

Command:

cd Documents

Go back:

cd ..

Go home:

cd ~

Example:

Like moving from one room to another inside a house.

4. Create a Folder

Command:

mkdir Projects

Create multiple folders:

mkdir HTML CSS JavaScript

5. Remove Folder

Empty folder:

rmdir Projects

Folder with files:

rm -r Projects

Be careful:

rm -rf

This permanently deletes files.

6. Create Files

Using touch:

touch notes.txt

Create multiple files:

touch file1.txt file2.txt file3.txt

7. Delete Files

rm notes.txt

Delete multiple:

rm file1.txt file2.txt

8. Copy Files

cp notes.txt backup.txt

Copy folder:

cp -r Projects Backup

9. Move Files

mv notes.txt Documents/

Rename file:

mv old.txt new.txt

10. View File Content

Display:

cat notes.txt

Long file:

less notes.txt

Beginning:

head notes.txt

End:

tail notes.txt

Live logs:

tail -f logfile.log

11. Search Files

find . -name “*.php”

Example output:

./website/index.php

./admin/login.php

12. Search Text

grep “password” config.php

Case insensitive:

grep -i error logfile.log

13. Check Disk Usage

df -h

Shows:

• Total storage
• Used storage
• Free storage

14. Check Folder Size

du -sh Downloads

Output:

3.5G Downloads

15. Check Memory Usage

free -h

Shows:

• RAM
• Used memory
• Available memory

16. View Running Processes

ps

More detailed:

top

Modern version:

htop

17. Kill a Process

kill 1250

Force kill:

kill -9 1250

18. Check IP Address

ip addr

Older command:

ifconfig

19. Test Internet Connection

ping google.com

Stop:

Ctrl + C

20. Download Files

wget https://example.com/file.zip

Alternative:

curl -O https://example.com/file.zip

21. Install Software

Ubuntu:

sudo apt update

sudo apt install git

Fedora:

sudo dnf install git

Arch Linux:

sudo pacman -S git

22. Update System

Ubuntu:

sudo apt update

sudo apt upgrade

23. File Permissions

View:

ls -l

Example:

-rwxr-xr–

Meaning:

• Owner permissions
• Group permissions
• Others permissions

Change permissions:

chmod 755 script.sh

Make executable:

chmod +x script.sh

24. Change Ownership

sudo chown username file.txt

25. Check Current User

whoami

Output:

student

26. System Information

uname -a

Kernel version:

uname -r

Operating system:

cat /etc/os-release

27. Clear Screen

clear

Shortcut:

Ctrl + L

Scenario Organizing a Web Development Project

Suppose you’re building a website.

Step 1: Create a project folder

mkdir MyWebsite

Step 2: Enter the folder

cd MyWebsite

Step 3: Create project files

touch index.html style.css script.js

Step 4: Verify files

ls

Output:

index.html

style.css

script.js

Step 5: Create an images folder

mkdir images

Step 6: Move into images

cd images

Step 7: Return to the project root

cd ..

Step 8: Create a backup

cp -r MyWebsite MyWebsite_Backup

This demonstrates how developers manage projects efficiently using the Terminal.

Tips

• Practice commands in a safe directory.
• Double-check before using rm -rf.
• Use the Tab key for auto-completion.
• Press the Up Arrow to reuse previous commands.
• Use man <command> to read a command’s manual page (for example, man ls).
• Use –help to see quick usage information (for example, cp –help).

Common Mistakes

Conclusion

Terminal commands are a fundamental skill for Linux users, system administrators, developers, cybersecurity professionals, and DevOps engineers. By mastering commands for navigation, file management, permissions, networking, and software installation, you can work more efficiently and automate complex tasks. Start with the basics, practice regularly, and gradually build confidence using the command line.

FAQ