Oh boy, somebody without knowledge about UNIX commands will be so lost :D
I enjoyed the little puzzles and getting to the bottom of this, though I personally think that time constraint is not adding much (especially, since the knowledge persists - if you know a password, you can use it next time you play, etc.).
Also, I have a muscle memory of using "ll" instead of "ls", so I was getting errors every 10 seconds because of it :D