The first non-windows system I installed was FreeBSD and later on moved to slackware and then other linux distros. I would really recommend FreeBSD to a novice

The first non-windows system I installed was FreeBSD and later on moved to slackware and then other linux distros. I would really recommend FreeBSD to a novice who'd like to install an un*x and really understand how it works. It's mostly the same steps as slackware but 1/ FreeBSD docs are godly (I didn't have internet at the time and managed to do all I wanted with just the FBSD user manual, I hope it hasn't changed since then) and 2/ Slackware is sometimes hard to get to work for the wrong reasons. Lack of proper dependency tracking in the package manager for instance is just insane unless you only plan to install a couple packages or you plan to spend your life manually installing and updating your packages (or never update which seems to be how most slackware users deal with that in my limited experience). In the end I don't think it requires more skill to properly set up a slackware install versus some BSD or even Gentoo or Arch. And if you don't really care about having a maintainable OS and just want to know how everything fits together in a modern linux system you might as well try Linux From Scratch, it's meant for that.