Guide to Unix/Commands/File Editing
Basic editing of system files.
Nano is a clone of Pico. Pico (text editor) is an easy-to-learn text editor originally designed for composing e-mail in Pine.
A light-weight, feature-reduced clone of emacs.
A powerful editor based on ex. For details see the Wikibooks Learning the vi Editor.
A very powerful editor that is used by many programmers.