Frustrated penguin
Ah-ah, I'm exaggerating this thing. The reality is that I tend to forget many details of their syntax and behavior, so I will put here what I learn, maybe it is useful also to someone else. By the way, if you want to learn how to use the Linux terminal (bash), it is very useful to install on your machine a Linux distribution with no desktop manager, but only a terminal, X server, and fundamental programs. I used gentoo Linux with a minimal set of program. It is very difficult to install, but at the end you will learn a lot of things. Of course, you have to spend a lot of time on it.
General rule: search engines are your friends.