Linux.com: You’ve Got a Friend in Grep!

“Ever been typing at the console, experimenting with commands?
You try a command here, a command there, and jot down what you
think each one does. Then, you come across one command that spurts
out a long line of cool looking text, which scrolls past your
terminal’s viewing limit. You scroll up and down, perhaps looking
for a particular string of text to tell you that your video card or
network is set up properly. Wish there was an easier way? Well,
there is – GREP!”

“Grep stands for (G)lobal (R)egular (E)xpression (P)arser. This
information isn’t really necessary, but it’s a cool little fact to
tell to your friends. You’ll wow them with your brain power! Don’t
waste any mental energy trying to figure out exactly what this
means, as you will probably turn red in the face and fall over.
To simplify the definition, grep basically displays lines of
text in a file that match the search pattern you specify.

Mental gears still slipping? This analogy might help:”

“Pretend you have a screen on a window. You want to allow only
ONE type of bug into your house, but leave all the rest outside.
This screen allows you to customize the openings so that only the
bug of YOUR choice can enter your house. Grep is like this screen.
It will search the output of a command (or the contents of a file),
and only show you the lines of text in that command or file that
match your customized search string.”