Ask HN: UNIX / Command Line tutorial for non-dummies

Dear HN: I've recently begun the process of hosting a website for a friend on mine. He'll just be running a wordpress install, but I'm giving him shell access and it would be nice if he was able to do basic php and css config himself if he needs to. That said, he has basically no UNIX experience. He's not a computing novice - he's currently working through a python programming course, for instance - but he's never used GNU/Linux, and whatever OS X experience he has is pretty superficial. Do you all have any favorite tutorials to get him up to speed with sshing into GNU/Linux shell account running bash?