Global Regular Expression Print is a staple of every command-line user’s toolbox. As with find, it derives a lot of power from being combined with other tools and can increase your productivity significantly.
Following is a simple tutorial that will help you realize the power of this simple and most useful command. If you are on Windows and haven’t already, download and install Cygwin. If you are also new to regular expressions (regex), here is a great regular expressions reference to get you started.