> Use man to learn about each tool

> Learn regex and posix for syntax related to most shell commands.

> Learn primary tools like grep, sed, awk, and find. You can do a lot with grep and sed.

> Read up on bash scripting.

> Learn the difference between | and & and && and ; when used in a command. You'll be using those a lot.

> Use forums like superuser.com or stackoverflow.com

> Read arch wiki when you have a question, even if not using arch. It will at least give you ideas.

A lot of linux is learning to solve YOUR issues and brainstorming or researching those solutions. There's no generally learning linux.