Sed

Sed is a *nix system utility that will come with 99% of *nix systems. It's an in-place string manipulation program that can come in handy to make a whole lot of typing into a few lines of string manipulation. It's ugly, but once you start to use it you'll wonder how you ever lived without it.

Sed introduction and tutorial: http://www.grymoire.com/Unix/Sed.html