[expert] I just don't "grep" this...

[Mark Weaver]

Hi list,

I know I've used this utility before, but you know what?...I really have
no idea for sure what the little bugger is. I've taken it for granted
that it's in there and used it as I've seen it exampled. 

So, could someone provide a definitive explanation of just what exactly
grep is, where I might find some real thorough information on usage and
function on this wonder of hidden technology?

thanks,

Mark