A Linux operating system isn’t a single entity, but a collection of files, scripts and executables that work together to present an interface and manage the underlying environment. Together, those assets are known as a distribution, or “distro”. Whichever flavour of Linux you choose to install, it will have several recognisable components in common with its rivals.
Kernel
This is what it all comes down to. Without the kernel, there would be no Linux. It sits directly above your hardware to provide an interface between the software layer and your processor, memory, storage and so on. It can be added to on the fly as and when the system needs to access a device driver, and its similarity to Unix is what defines Linux as a Unix-like operating system, rather than simply the commands used or its look and feel.
The kernel is developed collaboratively by a distributed team of coders who adapt it for use on different architectures, including x86 and ARM. Spin-offs form the basis of similar (although not identical) operating systems such as Android and webOS.
Package manager
Packages are apps and, logically, a package manager handles installing, updating and removing them from your system. Traditionally, this would have been done at the command prompt (via the terminal), although graphical package managers, which vary between distributions, now give the process a friendly front end, and a graphical environment like that found in the Microsoft and Apple software stores. Packages are installed from software repositories.
Although Linux is used as a generic term for a collection of operating systems, they don’t all work in the same way, and one of the biggest points of difference is the workings of their package managers – and which manager their developers have chosen to implement.
As an example, the table below shows how you would perform a range of common package management tasks via terminal using apt (common in Debian-based distributions, including Ubuntu and Raspbian), pacman (used by Arch-based distributions such as Manjaro) and RPM (which you’d encounter when running Red Hat or Fedora).
| Row 0 - Cell 0 | Install package | Upgrade package | Uninstall package |
| APT | apt install [name] | apt upgrade [name] | apt remove [name] |
| pacman | pacman -S [name] | pacman -R [name] | |
| RPM | rpm -i [name] | rpm -U [name] | rpm -ev [name] |
Window server
The window server is what makes Linux approachable for novice users, transforming it from a text-based OS into a fully graphical environment. Effectively, it interprets the GUI, which is rendered by the window manager, and translates clicks and mouse movements into actionable commands. On Linux, the most common window server is known as X, X11 or the X Window System, which has been in active use since 1984.
Window manager and desktop environment
These are like a Linux distribution’s style book. It’s the code that defines what you see onscreen, from window borders and controls, to docks and app launchers, the way they behave, how they give feedback and so on. As with the package manager component, there are several window managers to choose from, although in this case end users frequently have greater latitude, with the option to download each distribution tailored for use with a range of different window managers.
Common desktop environments include Gnome, KDE and Xfce. Choosing between them is often a matter of preference, although some may be better suited to specific use cases. Xfce, for example, is optimised for speed and running on less powerful hardware – much like MATE, which started as a form of GNOME 2.
Applications
At this point, things become more subjective. Although applications aren’t a core part of the operating system – in that each would boot and run without apps, even though it wouldn’t be much use – distribution developers each bundle a selection of useful software to get you started. At the most basic, this usually consists of an office suite, web browser and email application, with the most common being LibreOffice, Firefox and Thunderbird respectively.
However, the distribution installers frequently give the option of standard and minimal install options, the latter of which sets up just the guts of the OS and leaves the end user to assemble their preferred software selection after first boot using the command-based package manager or graphical app store.
