Before looking at GNU/Linux distributions and the place this system occupies in contemporary computing, it's important to trace its origins in order to understand what it represents. In this chapter, we look back at the historical, philosophical and technical roots of GNU/Linux, through the legacy of Unix, the genesis of the GNU project, the creation of the Linux kernel and the emergence of the free software movement.

The birth of Linux cannot be understood without mentioning its direct ancestor: Unix. Created in the late 1960s and early 1970s by Ken Thompson, Dennis Ritchie and their colleagues at AT&T Bell Labs, Unix marked a major turning point in the history of operating systems. Initially developed in Assembler, then rewritten in C by Dennis Ritchie in 1973, Unix laid the foundations for a radically new OS model based on modularity and simplicity.

This approach is reflected in the founding principle articulated by Doug McIlroy:

Unix can be seen as an evolution of, and reaction to, the Multics operating system, whose architecture it adopts. Multics was a project initiated in 1964, the fruit of collaboration between MIT, General Electric and AT&T Bell Laboratories. Ken Thompson and Dennis Ritchie (the creators of UNIX) kept a close eye on the Multics project until 1969, when their company withdrew from development.

It was at this point that Unix emerged, initially named "UNICS" for "UNiplexed Information and Computing Service", in direct opposition to "MULTiplexed Information and Computing Service", the acronym for Multics. This new approach advocates simplicity, modularity and efficiency, in contrast to the excessive complexity of Multics.

From the 1970s onwards, Unix developed in a research context, before being widely distributed in universities from 1975 onwards, not least because of the antitrust restrictions imposed on AT&T. This favored its adoption in many laboratories, such as Berkeley, where the BSD (Berkeley Software Distribution) branch was born. At the same time, AT&T began marketing Unix in the 1980s, leading to a proliferation of incompatible proprietary versions (System V, Xenix, SunOS, AIX, Solaris, HP-UX, etc.).

The growing fragmentation between these branches (BSD on the academic side, and System V in particular on the industrial side) created considerable confusion and limited system interoperability. To find a stable, portable, royalty-free equivalent of Unix, the community launched several initiatives, including the GNU project in 1983, followed by the development of the Linux kernel in 1991, which filled the gap left by the absence of a free kernel in the GNU ecosystem. This was the starting point for the GNU/Linux system.

The GNU project (a recursive acronym for "GNU's Not Unix") was officially announced by Richard Stallman on September 27, 1983, in specialized newsgroups. At the time, Stallman was still working at MIT's Artificial Intelligence Laboratory. On January 5, 1984, he voluntarily resigned from his position to ensure that the code he was about to write could not be claimed by his employer. He then began development of GNU, with the aim of creating a completely free operating system, i.e. one that respected four fundamental freedoms: free execution, free study, free modification and free redistribution.

Beyond its technical aspects, the GNU project is part of a philosophy inherited from the hacker culture of the 1970s: a culture based on knowledge sharing, peer cooperation and free access to source code. Richard Stallman wanted to preserve the spirit of collaboration that dominated the early days of computing, when manufacturers still freely distributed the source code of their systems. The GNU project aims not only to offer a free operating system, but to defend a political and ethical vision of computing: that of knowledge accessible to all, without monopoly or proprietary lock-in. The aim is to prevent users from becoming prisoners of software they can neither understand nor modify, and to promote emancipatory computing.

With this in mind, Stallman founded the Free Software Foundation (FSF) in 1985, an organization dedicated to encouraging and promoting the use and creation of free software.

GNU quickly provides a series of essential tools for its system:

Some external bricks are also integrated, such as the X Window System, the TeX composition engine and the Mach microkernel, used with the GNU Hurd server package (together, Mach and Hurd fulfill the same roles as a classic Unix kernel, but in a microkernel + server architecture). This kernel replacement project was ambitious but highly complex. It will never become fully functional, leaving room for the Linux kernel.

Most of GNU was developed by volunteers, some in their spare time, others funded on an ad hoc basis by companies, universities, or associations. At the end of the 1980s, the FSF began to hire developers to speed up the work. Some companies, such as Cygnus Solutions (later part of Red Hat), played an active role in maintaining and marketing GNU Free Software.

When Linus Torvalds published his Linux kernel in 1991, it fitted in perfectly with the environment already created by GNU, and proved to be far more relevant than the Mach + Hurd kernel. The combination of GNU and Linux made it possible for the first time to have a complete, free and functional operating system: GNU/Linux, the practical realization of the project launched by Stallman almost a decade earlier.

The story of the Linux kernel begins in 1991, with Linus Torvalds, then a computer science student at the University of Helsinki, Finland. Dissatisfied with the limitations of Minix, a minimalist Unix operating system designed by Andrew S. Tanenbaum for educational purposes, Torvalds set about developing his own kernel for his personal computer, simply with the aim of learning by doing. On August 25, 1991, he publicly announced his project on the Usenet forum, modestly stating that it was still rudimentary and experimental. In early 1992, version 0.12 of the project was released under the GNU GPL free license.

This kernel, initially named Freax and later renamed Linux (a contraction of "Linus" and "Unix"), soon attracted the attention of other passionate developers. An international community spontaneously sprang up to contribute to the freely accessible source code. Unlike GNU, Linux is initially just a kernel: the software component responsible for managing the machine's hardware resources. Combined with the tools and applications already developed by the GNU project, this kernel finally provides a completely free and functional operating system. This combination is referred to as "GNU/Linux" to emphasize the synergy between the two projects. In common parlance, however, this operating system is generally referred to simply as "Linux".

→ Tux: the mascot and logo of the Linux kernel, created in 1996 by Larry Ewing using GIMP software.

As Linux gained in popularity in the 1990s, an ideological debate emerged around the terms "free software" and "open source", not least because of the double meaning of the term "free".

While Richard Stallman and the FSF strongly advocate the idea of free software based on ethical principles ("free as in freedom"), other players favor a more pragmatic, engineering-oriented approach focused on the transparency and technical efficiency of the open model. In 1998, the Open Source Initiative (OSI) was created, introducing the term "open source" in order to appeal more to the corporate sector, emphasizing economic and technical benefits rather than ideological considerations.

Richard Stallman openly criticizes the use of the term "open source", deeming it too neutral, even depoliticized. He insists on the term "free software" to emphasize that the central issue is not technical, but social: that of users' freedom.

The distinction between the two terms therefore lies in the underlying motivation: the free software movement primarily promotes a philosophy of individual and collective freedom with regard to software, while open source primarily values technical efficiency, transparency and collaboration as the means to a better product.

Despite their philosophical differences, these two currents share common values such as transparency, source code auditability, vendor independence, and the ability of end users to understand, modify and improve their software tools. Even today, these distinctions regularly fuel debate and reflection within technical communities, notably Bitcoin.

GNU and Linux are not just a technical success story: their cultural and social impact is just as important. Their initial spread was mainly via the Internet, through technical forums and mailing lists, then rapidly through distributions, i.e. pre-configured assemblies of software around the Linux kernel. As early as 1993, pioneering distributions such as Slackware and Debian were created to make the GNU/Linux operating system more accessible to a wider public.

This community-based, open and collaborative approach enables Linux to evolve rapidly, in a decentralized and participative way. Every user can contribute to the project, whether by coding, documenting or testing. This massive collaborative dynamic represents a major social innovation in the world of computing.

As we saw in the previous chapter, Linux's legacy today extends far beyond simple personal computers: it dominates the Internet server market, powers supercomputers, forms the technical basis of the Android system that powers billions of smartphones worldwide, and is even at the heart of countless everyday electronic devices (routers, smart TVs, connected objects, etc.).

GNU/Linux is much more than just an operating system: it's a philosophy, a technological, cultural and social approach founded on openness, collaboration and digital freedom. These values continue to profoundly influence the way we conceive, use and share technologies today.

In the light of this technical heritage, it's now possible to examine in concrete terms how these principles materialize in today's personal computer ecosystem. To this end, we're going to explore the vast landscape of Linux (or GNU/Linux) distributions, to understand their evolution and use cases, and to help you choose the one that best suits your needs.