Chapter 1: Inside the Linux World

Foreword

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Introduction

Future hacker? Future Linux system administrator? Future DevOps? Just curious? Passionate about computers? Let’s explore the wonderful world of Linux together. Linux, the famous open-source operating system that everyone fears.

1. History of Linux

Linux was born in 1991, created by Linus Torvalds, a Finnish student inspired by UNIX, a powerful and modular operating system developed in the 1970s by Ken Thompson, Dennis Ritchie, and others at Bell Labs. UNIX was renowned for its stability and portability, but its code was not free. Torvalds wanted to recreate a similar system that was free and open, so he published the Linux kernel and shared it with the community. By combining it with tools from the GNU project (launched by Richard Stallman in the 1980s to create a free operating system similar to UNIX), Linux became a complete operating system, often referred to as GNU/Linux. It inherited concepts such as multi-user management and multitasking from its UNIX roots, while evolving thanks to open source. Today, Linux dominates the market for servers, supercomputers, and even smartphones (via Android), often surpassing UNIX in popularity.

Let’s recap the key points to remember:

Short Exercise

2. Linux distributions

Now you know what Linux is. You may be wondering how to install it. Installing Linux involves three main steps.

  1. Choosing a distribution (Debian? Ubuntu? Kali Linux? Linux Mint? Arch Linux, etc.)
  2. Choosing an installation method (main OS? Dual boot? Virtual machine? Cloud?)
  3. Installation 🙃​

Let’s talk about Linux distributions

Linux is installed via a distribution. A Linux distribution (or “distro”) is a complete, ready-to-use version of the Linux operating system, built around the Linux kernel. It includes not only the kernel, but also a set of software, tools, libraries, and often a user interface (such as a desktop environment), all tailored to specific needs. It should also be noted that each distribution has its own particularities.

In the Linux world, we talk about parent distributions. A parent distribution is a Linux distribution that serves as the basis or starting point for other derivative distributions. These “parents” are often stable, well-established, and provide a technical foundation on which other projects build their own versions, adding customizations or specific objectives.

Examples of parent distributions

NB: Some distributions have a default user interface, others do not (when the system starts up, you land directly on a command line interface).

A Linux distribution (Ubuntu 24.04) with a user interface may look like this:

A Linux distribution without a user interface may look like this:

Info: In general, Linux is installed on servers without a user interface. Management is therefore done via the command line only.

The major differences between distributions

We will compare distributions according to three criteria: package and update management, philosophy and target audience, and ease of use.

  1. Package and update management

    • Debian: Uses the apt manager (.deb format). Prioritizes stability with less frequent but rigorously tested updates. “Stable” versions may include older software.
    • Red Hat: Uses yum or dnf (.rpm format). Enterprise-oriented, with long cycles (RHEL) to ensure stability. Fedora, its derivative, is more up-to-date and experimental.
    • Arch Linux: Uses pacman. “Rolling release” model: continuous updates, always cutting edge, but less stable if poorly managed.

  2. Philosophy and target audience

  1. Ease of use

💡 A secondary criterion that could be added is the specificity of the distribution: some are security-oriented (hacking/pentesting), others are geared towards gaming, or designed for everyday use (generalists) or adapted to less powerful machines (lightweight).

With freedom at the heart of Linux, each distribution has its own objectives, philosophies, history, and package manager.



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