The History of Linux

Linux did not appear out of nowhere. It is the latest chapter in a story that starts decades before Linus Torvalds ever wrote a line of kernel code. Knowing that story makes the why behind Linux's design - "everything is a file," small tools piped together, free and open source - make a lot more sense.

Before Linux: Unix (1969)

In 1969, Ken Thompson and Dennis Ritchie at Bell Labs (AT&T) started building a new operating system, later named Unix. A few years later they rewrote it in a new language Ritchie designed for the job: C. That decision is why Unix - and everything descended from it, including Linux - could run on wildly different hardware with only small changes: the OS was no longer tied to one machine's assembly language.

Unix introduced ideas that still define Linux today:

• Everything is a file - devices, pipes, and many kernel interfaces are accessed through the filesystem.
• Small tools, composed together - one program does one job well; pipes (|) chain them into pipelines.
• A multi-user, multi-tasking system from the start, with permissions built in.

The Unix family splits (1970s-1980s)

AT&T licensed Unix to universities and companies. The University of California, Berkeley produced its own variant, BSD (Berkeley Software Distribution), adding features like the vi editor and TCP/IP networking. Commercial vendors then built their own Unix flavors on top of AT&T's code - Sun's SunOS/Solaris, HP-UX, IBM's AIX, SGI's IRIX - each proprietary, each incompatible in its own small ways. By the mid-1980s "Unix" had splintered into a family of similar but license-encumbered systems, none of them free to study, share, or modify.

The GNU Project (1983)

In 1983, Richard Stallman announced the GNU Project ("GNU's Not Unix") with a specific goal: build a complete, Unix-compatible operating system that was free software - free to run, study, share, and modify. Over the next several years the project produced the essential tools: the gcc compiler, the bash shell, and the GNU coreutils (ls, cp, grep, and the rest of the commands you've already been using in this course).

GNU had almost everything a full operating system needs - except the kernel, the core piece that talks to hardware and manages processes and memory. That piece was still missing in 1991.

The Linux kernel is born (1991)

On August 25, 1991, a 21-year-old Finnish student named Linus Torvalds posted to a Usenet newsgroup:

"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones."

That "hobby" was the Linux kernel. Torvalds released it under the GNU General Public License (GPL), which meant it could legally be combined with the GNU tools that already existed. The result - the Linux kernel plus the GNU userland - formed a complete, free operating system, properly called GNU/Linux, though most people just say "Linux."

Distributions emerge (1993-1996)

A bare kernel plus loose GNU tools isn't something most people can install. A distribution ("distro") packages the kernel, the GNU tools, an installer, and a package manager into one coherent system:

Growth through the 2000s

Through the 2000s Linux moved from hobbyist curiosity to enterprise infrastructure. IBM invested a billion dollars in Linux development in 2000. Red Hat went public and built a business model around paid support for free software. In 2004, Ubuntu launched with a mission to make Linux approachable on the desktop, and quickly became the default recommendation for newcomers.

The single biggest growth moment of the decade had nothing to do with desktops or servers: in 2008, Google shipped Android, a mobile OS built on the Linux kernel. Within a few years, the Linux kernel became the most-deployed kernel on Earth by device count - not because of servers or desktops, but because of phones.

systemd and the modern init system (2010s)

For decades, Linux distributions started services at boot using SysV init, a design inherited from Unix - plain shell scripts run in sequence. Starting around 2010, systemd offered a replacement: parallel service startup, dependency-based ordering, unified logging (journalctl), and one consistent systemctl command to manage everything. It was controversial - critics argued it strayed from the "small tools" Unix philosophy - but by the mid-2010s nearly every major distribution (Debian, Ubuntu, Fedora, RHEL, SUSE, Arch) had adopted it as the default. It remains the standard today; you'll use it yourself in the systemd lesson.

The cloud and container era (2013-present)

Two Linux kernel features quietly enabled the next revolution: namespaces (isolating what a process can see) and cgroups (limiting what resources a process can use). In 2013, Docker packaged those primitives into an easy developer workflow: build an image, run a container. In 2014, Google open-sourced Kubernetes to orchestrate fleets of containers across many machines.

The result: virtually the entire cloud - AWS, Google Cloud, Azure, and every major hosting provider - runs on Linux. Every one of the world's 500 fastest supercomputers runs Linux. Most web servers on the internet run Linux. Counting servers, phones, and embedded devices together, it is by a wide margin the most-used operating system kernel in the world.

Linux on new frontiers

• Chrome OS (2011) - a Linux-based OS built around the Chrome browser, common in schools.
• Windows Subsystem for Linux / WSL (2016) - Microsoft shipped a real Linux kernel inside Windows, letting Windows users run this exact command line without dual-booting.
• Steam Deck / SteamOS (2022) - a Linux distribution built for gaming, proof Linux gaming has gone mainstream.

Linux today

Modern Linux keeps evolving: immutable, image-based distributions (Fedora Silverblue, openSUSE MicroOS) that update atomically and roll back safely; Wayland gradually replacing the decades-old X11 display server; and, in recent years, Rust code accepted directly into the kernel alongside its traditional C - the first new systems language let into Linux's core since C itself. Linus Torvalds still leads the kernel's development today, coordinating thousands of contributors from companies and individuals worldwide, on a predictable release every 9-10 weeks.

From a hobby project announced almost apologetically on Usenet in 1991, Linux has become the operating system underneath most of the internet, most of the world's phones, and most of the world's supercomputers - all while remaining free, open source software anyone can read, modify, and run.

Further reading

• "Just for Fun" by Linus Torvalds and David Diamond - Torvalds' own account of building Linux and the culture that grew around it.
• "The Cathedral and the Bazaar" by Eric S. Raymond - the classic essay on why Linux's open, chaotic development model worked.
• "Free as in Freedom" by Sam Williams - a biography of Richard Stallman and the free software movement behind the GNU tools Linux depends on.