I have been using Linux as my daily driver for quite some time (around 5-6 years) and usually manage to get whatever needs to be done. However, I now wish to learn it in a more structured manner, which includes understanding utilities and the workings of Linux. What resources should I look out for?
Highly recommend this wargame challenge from over the wire. It makes you think and also feels like hacking. Youre just using linux commands to find passwords but the skills transfer to heaps of usage across systems. It can be a little beginner-ish though.