If you’ve ever used a system shell before (the Terminal application on Mac’s and most Linux OS’s), you know how powerful they can be. If you haven’t, the system shell (also called the command line), is basically another method of controlling a computer. Just as you normally open programs, edit documents and manage files, the same can be done in a shell. However, all will be done using only text called commands. The simplicity and elegance of the shell is why it’s loved by many.