I'm pretty new to the industry, being young, but as soon as I got a machine to run a Linux VM on, I spent hours reading docs and man pages and books on Bash and general *nix commands. Definitely helped me become a better programmer. It's amazing what you can do with simple POSIX commands. I didn't even know about sort until now, but it'll help me a bunch now.
Run `info coreutils` and get a general sense of the tools available. There are things you'll use all the time like sort, uniq and wc. Things you'll use occasionally (`foo | column -s $'\t' -t` reads all the lines of standard input, splits each on a tab and then lines everything up in nice columns) and things you might rarely need, but when you need them they're amazing: tsort, for example, is really useful for managing dependencies in certain circumstances.
