Linux Command Line Free Training

The Video series by Wes Bos is very informative Linux Command line power user. I would recommend running the video at 1.5 speed and simultaneously practising the commands whilst looking at the vide. You can use an online command terminal like this  Linux online terminal  He goes into sufficient depth with just one short video. For more commands, you can try the first couple of pages from Learn Enough Command Line to Be Dangerous