🔳 Do you know what CLIs are? Let's find out together.

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When talking about computer science, especially programming or systems administration, you often hear about CLIs. For many beginners, this term might seem complicated or even "scary," but in reality, CLIs are powerful tools and, once understood, very simple to use.

In this article, we will see what CLI means, why it is so important, which are the most famous CLIs across various operating systems, and finally how to use them concretely, from startup to the most useful commands explained step-by-step.

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What does CLI mean?

The acronym CLI stands for Command Line Interface.

In simple terms, a CLI is a way to communicate with a computer by typing text commands, instead of using a mouse to click on icons and windows (as happens in graphical interfaces, called GUIs – Graphical User Interface).

CLI vs Graphical Interface

  • Graphical User Interface (GUI):
    You click on icons, buttons, and menus (Windows, macOS, Linux desktops).
  • Command Line Interface (CLI):
    You write text instructions that the system executes.

Example:

  • GUI: you click on a folder to open it
  • CLI: you write a command that tells the computer "open this folder"

Why are CLIs so important?

CLIs existed before graphical interfaces and are still fundamental today because:

  • they are fast
  • they allow for precise control of the system
  • they are automatable (scripts)
  • they work even on computers without a graphical interface
  • they are the standard for servers, software development, and cybersecurity

Many advanced operations are only possible or better handled via CLI.


The most famous CLIs across various operating systems

Every operating system has one or more integrated CLIs.

Windows

  1. Command Prompt (CMD)
    • The historical Windows CLI
    • Simple but limited
  2. PowerShell
    • More modern and powerful
    • Supports advanced scripting
    • Standard on Windows 10 and 11

macOS

  1. Terminal
    • Based on UNIX
    • Very similar to Linux
    • Extremely powerful and widely used by developers

Linux

Linux is strongly CLI-oriented. The most common ones are:

  • Bash
  • Zsh
  • Fish

The CLI is a central part of the Linux experience.


How to start a Command Line

Let's see how to open the CLI on various systems.

On Windows

Method 1 – Command Prompt

  1. Press Win + R
  2. Type cmd
  3. Press Enter

Method 2 – PowerShell

  1. Press Win + X
  2. Select "Windows PowerShell" or "Terminal"

On macOS

  1. Open Finder
  2. Go to Applications → Utilities
  3. Click on Terminal

Or use Spotlight:

  • Press Cmd + Space
  • Type Terminal
  • Press Enter

On Linux

Usually, it is enough to:

  • Press Ctrl + Alt + T

Basic structure of a CLI

When you open a CLI, you will see something like:

user@computer:~$

This line indicates:

  • the username
  • the computer name
  • the current folder
  • the symbol $ indicates you can type a command
In Windows, this line might simply show the path where the CLI was opened:

CLI prefix in Windows

Fundamental commands (for beginners)

1. pwd – Where am I?

pwd

Means: Print Working Directory
Shows the path of the folder you are currently in.

Example:

/home/user/Documents

2. ls (macOS/Linux) / dir (Windows) – List files

ls

or on Windows:

dir

Shows all files and folders present in the current directory.

dir

3. cd – Change directory

cd Documents

Enters the "Documents" folder.

cd ..

Goes back to the parent folder (or the previous one if executed after cd <folder_name>).

This command is essential for navigating the file system.

4. mkdir – Create a folder

mkdir new_folder

Creates a new folder called new_folder.

5. touch (macOS/Linux) – Create a file

touch file.txt

Creates an empty file named file.txt.

On Windows (PowerShell):

New-Item file.txt
New-Item file.txt

6. cp / copy – Copy files

macOS/Linux:

cp file.txt copy.txt

Windows:

copy file.txt copy.txt

Copies file.txt to copy.txt.

7. mv / move – Move or rename

macOS/Linux:

mv file.txt new_name.txt

Windows:

move file.txt new_name.txt

Used both for moving files and for renaming them.

8. rm / del – Delete files (WARNING)

macOS/Linux:

rm file.txt

Windows:

del file.txt

⚠️ Warning: files deleted via CLI do not go to the trash but are permanently deleted immediately.

9. clear / cls – Clear screen

macOS/Linux:

clear

Windows:

cls

Used simply to make the screen tidier.

10. help / --help – Ask for help

Windows:

help

macOS/Linux:

ls --help

Shows all available options for a command.


Why learn CLIs today?

Learning to use a CLI means:

  • understanding better how the computer works
  • working faster
  • gaining skills in high demand in the IT world
  • feeling more confident and independent

Even if it seems difficult at first, just a few commands are enough to become productive.


A tip before finishing: man

What is man

man stands for manual and is the command used on Linux and macOS to read command documentation directly from the terminal.

Example:

man ls

Shows the complete manual for the ls command.

man on Linux and macOS

✅ Present by default

On:

  • Linux
  • macOS

man is always available and is the standard for consulting:

  • command description
  • syntax
  • options
  • examples

man on Windows

❌ On native Windows, unfortunately, man is not directly supported:

  • CMD → ❌ man does not exist
  • PowerShell → ❌ man does not exist

Windows uses a different system:

Get-Help command

Example:

Get-Help Get-ChildItem

✅ When man DOES exist on Windows

man is available on Windows only if you use a Unix-like environment.

1. WSL (Windows Subsystem for Linux) – RECOMMENDED

With WSL, you install a real Linux distribution on Windows.

In this case:

man ls

✅ It works exactly like on Linux

2. Git Bash

If you install Git for Windows, you will have:

  • Git Bash
  • partial support for man

It works for many Unix commands:

man git

3. Cygwin / MSYS2

Unix environments on Windows:

  • man available
  • more advanced / technical use

Summary Table

System man available
Linux ✅ Yes
macOS ✅ Yes
Windows CMD ❌ No
Windows PowerShell ❌ No
Windows + WSL ✅ Yes
Git Bash ✅ (partial)

Conclusion

CLIs (Command Line Interface) are a fundamental tool in modern computer science. They are not just for "geeks" or expert programmers: with the right explanations, anyone can learn to use them.

If you started today, you are already one step ahead 🚀
The command line is not an enemy: it is a powerful ally 😉



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