It's a shame that regular expressions are so often associated with Perl, as though they're a single topic. It's like speaking of astronomy and astrology in the same breath.
"so often"? Really? That must be a rather particular age bracket, as newer programmers probably don't know Perl at all (apart from its reputation), and the old Unix-heads know that Perl itself didn't really invent them (or basically anything, as Larry Wall would be the first to admit).
Sure, "Perl compatible" is a pretty common moniker (as in e.g. the "PCRE" library), as the POSIX (or original grep/sed) implementations are a bit anemic.
And I don't think any of them deserves to be compared with astrology, but don't particularly care to get into that argument again. About as worthless as vim/emacs/IDE discussions.
