Well, you have a good example there.
Personally, I keep files with examples of every terminal command that attracts my interest.
I usually open a terminal window & try out new ones I come across. I learn alot that way.
There are plenty of sources for terminal commands. You can find plenty by a forum search.
There are some threads of users sharing their favorites.
There is such an overwhelming amount of cli commands, that I gave up those studies. I find them in context right here, from real-life examples.
Your learning style may vary.
Try that forum search.
(search; command line, bash commands)
apt-get update && apt-get dist-upgrade