In terms of rapid upskilling the best advice I would give to someone whose anything like me (like to play)... is to try and get your head around scripting. Scripting is the next level from the command line (in that you use command line sytax in your shell scripts anyway) - so if you can get clever with scripts you'll get clever with command line syntax.

Make something.

Decide on something that sounds reasonalbly challengin - but not too over the top to start - then try and build a script. What you'll learn from trial and error, and using these forums will help you to upskill in a major hurry.

Might not be everyones cup of tea for learning - but it's the best way for me and its the way I learnt a lot in a small space of time.

Good Luck,.