After being away from the command line for years, I found I liked the following page as a quick cheat sheet to learn basic Unix, pretty much the same as Linux as far as commands:
http://freeengineer.org/learnUNIXin10minutes.html
I have a page with links to other, more extensive how-to's and tutorials for basic Linux newcomers.
http://sdjf.esmartdesign.com/new.html
The command line is my favorite place to be, but I will confess I got into just plain old bash scripting along with sed, no hard core programming now.
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