OverTheWire: Bandit Time to actually use the terminal. Bandit is a series of interesting level-based challenges that will help you learn useful commands! This will help you understand how powerful and useful the terminal is!
“… You will encounter many situations in which you have no idea what you are supposed to do. Don’t panic! Don’t give up! The purpose of this game is for you to learn the basics. Part of learning the basics is reading a lot of new information. …”
It is recommended to read through the instructions and man(ual) pages before getting started! Also, use the hints. Every level gives you a cheat sheet of “Commands you may need to solve this level”. Hit a wall? Research those exact commands.
Regex
Regex is your best friend for hunting down text patterns. Spend an hour learning it now, and it will instantly pay off in your daily Linux tasks and CTF solves. Check out this quick Bugcrowd guide to get the theory, then head over to Regex101 to actually practice writing them.