[tlug] f/grep question

[Jean-Christian Imbeault <jc@example.com>]

I'm trying to find files that contain '..' in them but not '...'. The 
following fgrep seems to find all files with '..' or '...' in them:

fgrep -rI ".." *

And this one will find all the files with '...' int them:

fgrep -rI ".." *

So I though in order to get *only* the ones with '...' a simple grep 
filter would work. But the following combination of fgrep with a grep 
filter to reject files with '...' doesn't seem to work:

fgrep -rI ".." * | grep -v "..."

I've always assumen that f/e/grep were pretty much the same programs. 
Are they not?

Also do fgrep and grep use different regular expression syntaxes?

Thanks,

Jean-Christian Imbeault