One way to get familiar with the command line is to run a personal website on your own server. Set up apache, set up ssh. Set up a firewall from the command line. Learn to read the error logs and access logs using the command line. Learn to make backups using rsync. Web + server admin gives you a lot of practical problems that can be effectively solved with the command line, and will give you a lot of real world experience.
I say that because I believe that the best way to learn a technology, is by needing it. Rather than just reading documentation, set yourself a problem to solve, then search for documentation about that problem and learn that way. Just reading documentation without a real need for it works too, but is less interesting and you will learn less from it. Running a website will give you a lot of practical problems to solve.
Try to set problems for yourself. Try to automate things you do often. And come back here and ask more specific questions. I don't say that to dismiss your current question. I really think that is the best way to learn.