2. The Linux terminal🔗

Throughout this guide we will mainly work by writting commands in the terminal. In layman terms, the terminal is a way to interact with the computer using only text. You certainly are used to interacting with the computer through graphical applications, clicking with your mouse here and there. In the terminal, there is no need for a mouse: everything is done through text commands. This may seem inconvenient at first, but actually it is a more powerful way to interact with the computer.

I will do everything in the terminal that is characteristic of GNU/Linux distributions. If you use GNU/Linux, great! We are on the same page. If you use MacOS, you are also good to go: the terminal and the operating system are very similar to GNU/Linux. There may be small changes in the commands I use, but Google can easily translate between the commands used here and the ones needed in MacOS. I will try to provide also the MacOS commands when needed, but I cannot guarantee they will work, since I don't have a Mac where I can test them (contributions in this line are welcome!). But what if you have Windows? Then you have to fully uninstall it, and then install a user-friendly GNU/Linux distro like Linux Mint or Ubuntu. Of course, I am (partially) kidding. There is a way to use a terminal like the one in Linux inside Windows. Below I briefly explain how.

What do you mean by a _GNU/Linux distribution_?

Strictly speaking, Linux is not the whole operating system. Linux is the kernel: the program that sits between the hardware and the rest of the programs, and coordinates things like files, memory, processes, and devices. Many of the basic command-line programs that make the system usable come from the GNU project. This is why you will often see the name GNU/Linux: a system built from the Linux kernel together with GNU tools and many other pieces of free software.

A distribution, or distro, is a packaged version of all that. A group of people takes the Linux kernel, the GNU tools, a package manager, installers, default configuration, graphical applications, updates, and documentation, and distributes them as a coherent system. This is what you usually call your operating system: the graphical interface and the whole suite of programs you get when you boot your machine. Ubuntu, Debian, Fedora, Arch, and Linux Mint are examples of distributions. They all belong to the same general family, but they differ in their defaults, in how you install programs, and in how much work they expect from the user. For instance, Linux Mint is user-friendly and ready to use out of the box. On the other hand, Arch Linux is a minimal distribution, that expects a user that is ready to build the whole system from the bottom up (I use Arch, btw).

Why is Windows different?

The short answer is that GNU/Linux and MacOS are both, in different ways, part of the UNIX family. UNIX was an operating system created at Bell Labs at the end of the 1960s. Many of the ideas that we still use in the terminal come from there: programs are started as processes, files are organized in a tree of directories, devices also look like files, small programs communicate through text, and a shell interprets the commands written by the user.

Linux was started in 1991 by Linus Torvalds as a free kernel inspired by UNIX. Together with the GNU tools, it became the GNU/Linux systems we use today. MacOS has a different, but related, story. Modern MacOS is based on Darwin, an operating system that contains many components from BSD, one of the historical branches of UNIX. So Linux is not UNIX, and MacOS is not Linux, but they share a lot of concepts and conventions.

Windows comes from a different lineage. Its history goes through MS-DOS and later Windows NT, not through UNIX. This is why many things look different there: paths use backslashes, drives have names like C:, the native command interpreters are different, and many standard UNIX tools are not available by default. This does not make Windows better or worse for every purpose, but it explains why the terminal experience is not the same. The section on WSL explains how to add a real Linux environment inside Windows, so that we can use the same tools without changing the whole operating system.

Really, what is a terminal?

People use the word terminal for several related things, and this can be confusing at the beginning. Historically, a terminal was a physical device with a keyboard and a screen that allowed a user to interact with a computer. We are talking about a time when graphical user interfaces (GUIs) did not exist. Today, when we say "open a terminal", we usually mean "open a terminal emulator": a graphical application that behaves like one of those old text terminals.

Inside that window there is normally a program called a shell. The shell reads the commands that you type, interprets them, starts other programs, and prints the result back on the screen. Bash is one particular shell, and it is the default in many GNU/Linux distributions. Zsh is another shell, and it is the default in modern MacOS. For our purposes, they are similar enough that we can ignore their differences.

The prompt is the little piece of text shown before the place where you type. It often contains your user name, the name of the machine, and the directory where you currently are; it usually looks like [username@hostname /path/to/dir]$. Finally, a command line interface, or CLI, is any interface where you use a program by typing commands instead of clicking buttons. The shell has a CLI, but it is not the only example. Many programs can be used from the command line: Git, Python, Lean, package managers, text editors, Codex, Claude Code, and many others. The terminal is just the place where we access many of these command line interfaces. So, in this guide, I will keep saying terminal in the everyday sense: the window where you write commands and read their output.

2.1. Windows Subsystem for Linux (WSL)🔗

This section is only for the Windows users.

WSL stands for Windows Subsystem for Linux. It is a Microsoft tool that lets you install a Linux distribution inside Windows and run Linux programs, utilities, and Bash commands from there. In practice, it gives you a Linux terminal without asking you to erase Windows, partition your disk, or manually configure a full virtual machine.

If you have Windows 11, or Windows 10 version 2004 or later, the installation is usually very simple. Open PowerShell as administrator, run:

Bashterminal

wsl --install

and restart the computer if Windows asks you to do so. By default, this installs Ubuntu. The first time you open it, Windows will finish the installation and ask you to choose a Linux user name and password. If you want another distribution, first run:

Bashterminal

wsl --list --online

to see the available options, and then install one of them with, for example:

Bashterminal

wsl --install -d Debian

After that, opening a Linux terminal is just opening the Linux distribution you installed. Press the Windows key, type Ubuntu (or Debian, or whatever distribution you chose), and open it like a normal application. You can also open Windows Terminal and choose your Linux distribution from the menu. If you already have PowerShell open, you can type:

Bashterminal

wsl

and press enter. When the prompt changes, you are inside the Linux system. To leave it and go back to PowerShell, type:

Bashterminal

exit

The official and up-to-date instructions are in the Microsoft WSL installation guide. Use them if any of the commands above fail, because Windows changes faster than this text.

For the purposes of this guide, WSL is more than enough. You can think of it as creating a new Linux system inside your Windows system. When you open WSL, you are not just opening a different-looking window: you are entering that Linux system, with its own files, programs, users, and directories. The safest habit is to do your work inside the home directory of that Linux system, written ~. Put your projects there, install your tools there, and run your commands from there. Windows files are still reachable from WSL, usually under /mnt/c, but we will not use that as our main working place.

2.2. Tasting the terminal🔗

Before we move on to more interesting stuff, let us get a feeling for how the terminal works.

First, open a terminal. In GNU/Linux, look for an application called Terminal, Konsole, GNOME Terminal, or something similar. In MacOS, open the application called Terminal. In Windows, if you followed the previous section, open the Linux distribution that you installed with WSL, for instance Ubuntu.

You should see an almost empty window with one line of text and a cursor waiting for you to type. That line is the prompt. It may look like [user@machine ~]$, or maybe like user@machine:~$.

The exact text does not matter. The prompt is just the shell saying: "I am ready, write a command". The last symbol is often $. You do not have to type it. In this guide, when I write a command, the $ will be shown by the terminal block, but the part you type is only the command itself.

Let us start with the smallest possible test. Type this and press enter:

Bashterminal

echo hello

Output

hello

The command is echo hello. The output is hello, the text printed by the command after you press enter. After the output, the prompt appears again. This is the usual rhythm of the terminal: write a command, press enter, read the output, and get a new prompt.

Now ask the terminal who you are:

Bashterminal

whoami

Output

username

Of course, your output will not be username, unless your user name happens to be username. It will be the name of your user in that system (inside WSL, your Linux user may have a different name from your Windows user).

Next, ask where you are:

Bashterminal

pwd

Output

/home/username

pwd means print working directory. A directory is what graphical interfaces usually call a folder. The working directory is the directory where the terminal is currently standing. Again, your output will probably be different, but it should have the same shape. If you are in a GNU/Linux or WSL system, it will often be something like /home/username.

The directory /home/username is your user's home directory. Since writing that full path all the time would be annoying, the shell uses the symbol ~ as an abbreviation for your home directory. So, when you see ~ in the prompt, it means that you are at home. This is not a metaphor. It means your personal working place in the system.

Let us look around:

Bashterminal

ls

ls lists the files and directories in the current directory. If the output is empty, do not worry. It only means that there is nothing visible there yet. If you see names like Desktop, Documents, or Downloads, those are directories.

We can also move to another directory. For instance, if Documents exists, try:

Bashterminal

cd Documents

cd means change directory. Notice that this command usually prints nothing. In the terminal, printing nothing often means that the command worked. To check where you are now, run pwd again:

Bashterminal

pwd

To go back home, run:

Bashterminal

cd ~

(or symply cd) and check again:

Bashterminal

pwd

That is enough for now. You have written commands, seen output, moved between directories, and met ~. If the screen starts to feel too full, you can clean it with:

Bashterminal

clear

or, in most terminals, pressing at the same time Control and l. This does not delete files or undo anything. It only cleans the terminal window, like erasing a blackboard. The previous commands are still in the shell history, and you can usually bring them back with the up arrow.

I hope you got a feeling for what the terminal is, and what does it look like to work on it. So let's move on to more interesting stuff.