Courses/LinuxAdmin/Distributions

When people start considering "Linux" as a solution (whatever the problem), one of the first question is "Where do I start", which quickly leads to "Which distribution should I use", even without understanding (and often wondering) what a "distribution" is.

Distributions (Ubuntu, Kali, Debian, RedHat, ... (find a certainly incomplete list on Wikipedia)) are only different ways to distribute the same softwares.

What is called a "distribution" is in fact a project shared with you by a (small or big) group of people to ease the installation, configuration, maintainance and upgrade of a (GNU/)Linux system.

The main differences between them is the packaging tool used to build and distribute the packages and the distribution (apt, emerge, pacman, yum, ...), and the configuration the package maintainers choose for each package. Aside from this, which represents a great work, but is nothing compared to the amount of of packages available, and is only a "side tool", not used by the "runtime" part of the system, the sources are the same. The shell bash is from the same source code (though the distributions sometimes add patches to some softwares), and will run the same on Debian, Kali, RedHat and so on. The kernel is also the same one (though the version and configuration will likely differ), with a libc on top of it and as a base for the whole userspace, and hundreds of userspace tools which you'll find on every distribution, which are the same, and work in exactly the same way. And more important, most of the time the kernel from one distribution can be used on any other one (in fact, it should ALWAYS be the case). This is one of the core principles of the UNIX philosophy and POSIX requirements. I hope this helps you understanding the GNU/Linux ecosystem a little bit more. If you haven't found a solution since your message, I can provide some support (I'm working as freelance).