Linux - Kernel or Operating System?

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To answer the question of whether Linux is, in fact, an operating system, we need to dive into a technical distinction that, while appearing as pedantry to many, defines the architecture of modern computing. The short answer is "yes" in colloquial and everyday usage, but "no" in a strict technical sense. To understand this duality, it is necessary to explore the history, software structure, and philosophy surrounding the Linux ecosystem.

At the center of it all is the kernel. Technically, Linux is just the kernel: the fundamental software layer that acts as an intermediary between the computer hardware and the applications the user runs. Imagine a car: the kernel would be the engine. The engine is the part that generates power and makes the vehicle move, but you cannot drive just an engine. You need a chassis, wheels, a steering wheel, a dashboard, and seats for it to be a "car."

The Linux kernel was created by Linus Torvalds in 1991. Its role is to manage system resources: it decides which program receives CPU processing time, how RAM is allocated, and how data is written to the hard drive. Without the kernel, software has no way to communicate with physical parts. However, the kernel alone does not offer a user interface, a text editor, or a web browser. This is where the definition of "operating system" begins to expand.

While Torvalds was developing the kernel in Finland, Richard Stallman and the Free Software Foundation (FSF) had already been working for years on the GNU Project. Stallman's goal was to create a complete and free operating system, similar to Unix. They had already developed almost all the necessary parts: code compilers (GCC), system libraries (glibc), command shells (Bash), and editing tools. They lacked, however, a functional and stable kernel.

When the Linux kernel was released under a free license, it became the missing piece of the GNU puzzle. The union of GNU tools with the Linux kernel resulted in a complete and usable operating system. For this reason, many purists and the FSF itself argue that the correct name for the operating system should be GNU/Linux. This nomenclature recognizes that Linux provides the low-level functionality (the engine), while GNU provides the environment and tools that make it an operating system in the broad sense.

Because Linux is modular and open-source, anyone can take the kernel, add a set of tools, a graphical interface, and a package manager to create their own system. This package is what we call a Linux Distribution (or "distro"). It is in distributions that Linux truly manifests as an operating system for the end user.

There are hundreds of distributions, each serving a different purpose. Ubuntu, for example, focuses on ease of use for home users. Debian prioritizes stability and the philosophy of free software. Arch Linux is aimed at advanced users who want to build their system from scratch. Kali Linux specializes in security and penetration testing. In all these cases, what the user installs is a complete operating system based on the Linux kernel.

The proof that Linux is a kernel and not a rigid operating system lies in its versatility. Android, the most widely used mobile operating system in the world, uses the Linux kernel. However, it does not use GNU tools. Google built its own interface, virtual machines, and libraries on top of the kernel. Therefore, although Android is "Linux-based," it is an operating system visually and functionally distinct from a computer running Fedora or Mint.

In the world of servers and supercomputing, Linux reigns supreme. The absolute majority of websites we visit, cloud services like AWS or Azure, and the 500 most powerful supercomputers on the planet run Linux. In these scenarios, it is the operating system par excellence due to its stability, security, and ability to be customized for specific tasks, eliminating everything unnecessary to gain performance.

The discussion about "Linux being an operating system" also touches on semantics. For the average user, if they turn on the computer and see an interface where they can open windows and browse the internet, that is the operating system. For this user, Linux is a competitor to Windows and macOS. And they are not wrong in their practical perception.

However, from a software engineering perspective, Linux is one part of a whole. Unlike Windows, where the kernel (NT) and the graphical environment (Windows Shell) are developed by the same company in an integrated way, the Linux ecosystem is a collaborative patchwork. You can swap the graphical environment (moving from GNOME to KDE), change the initialization system, or the sound server, and you will still be "using Linux" because the underlying kernel remains the same.

Therefore, to be precise: Linux is a kernel. However, through metonymy (the part representing the whole), the term "Linux" has come to designate any operating system that uses this kernel as its core.

Saying that Linux is an operating system is acceptable in everyday life and facilitates communication, but understanding that it is, in fact, the central component of a larger architecture helps us understand why it is so ubiquitous. It is in your router, your TV, your cell phone, and the servers that sustain the internet. Linux is not just an operating system; it is the foundation upon which modern computing was built, offering the flexibility necessary for developers to create entire operating systems tailored to every human need.