If you’re working with *nix systems, you will eventually come across the need to edit a file from the command line. Fortunately, most systems come with a plethora of text editors (Vi/Vim, Emacs, nano, etc.). Of these editors, the one that is more or less guaranteed to be installed is Vi. For a new user, learning to use Vi (or its modern incarnation, Vim) can be a daunting prospect. Fortunately, there are several excellent tutorials online, such as this one from Purdue.