I will be using your example of Arch as a great stepping off point, because honestly imo the best way to learn is by having a project to work on

1. RTFM - Read The Fucking Manual. Read the docs, read the code comments if need be. In the case of installing an OS, use the installation guide as a starting point; Arch’s is on their wiki, and links to several other sections that go more in-depth about what each step does and why it does it.

2. DuckDuck it - if you don’t understand what something is or why you’re doing it, search it. If you understand it completely, search it anyway and check the docs because no you don’t, you just don’t know how little you know. If you know why we do something and what function it fulfills, but not how… Then you’re a power user.

Using your example of commands from the internet, break the command down into as many parts as you can, and figure out what each part does. If there’s punctuation marks, don’t assume you know what those are doing. man [command's name] is your friend.

3. Do all of the above as often as possible, no matter how slow it makes progress feel. Learning these things the proper way now will save you from days, weeks and months of troubleshooting in the future. I mean it, literally at every step of the process.

4. secondary sources are invaluable, but for this it might help to get into the best way to self-educate. The only gospel are the docs and/or manual that were written by the code/OS maintainers - primary sources - everything else is opinion.

Here’s a source i agree with on the best way to self-educate, but keep in mind even Artem is still just a secondary source.

That being said, here’s a few secondary sources that helped me understand how OSes work and why:

nand2tetris: build an operating system starting with logic gates and working your way up from there. It has a offshoot site that’s slowly being rolled out, that implements it all in a gamified interface: nandgame

os-tutorial: build an OS from scratch

Linux From Scratch: Learn everything about Linux by building your own distro from the kernel up.

Unfortunately everything that taught about the behind-the-scenes aspects of OSes in general—and Linux in specific—were either projects like the above, or just seeing what came up in a DuckDuckGo, Youtube, forum, or wiki etc. search. Below are just resources that teach you about the “power user” level of knowledge, not “super user” but not your average user either.

Fireships’ 100+ Linux Things you Need to Know: it’s not particularly good on its own, but it does introduce a lot of concepts and vocab for you to then look up elsewhere

freeCodeCamp.org offers a lot of courses that will go over using Linux. None go too in-depth on the fundamentals of Operating Systems, but they will still introduce most of what you need to know for day-to-day use. I don’t want to link them all, but just search for linux freecodecamp on youtube and find one that piques your interest. The longer, the more in-depth—you don’t have to watch it all in one sitting.

5. And of course, when all else fails: just ask. Participate in the community, don’t be afraid of looking stupid. The only people that get no respect are the ones who refuse to accept others’ help because they know better than those they’re asking to help them. (ignore the gatekeepers who want to project their own need for an identity onto you)