The technique is actually quite simple. Basically, you're looking to do something like   $string =~ s/($pattern)/$1$stuffToAdd/g; where $pattern is something that will match across multiple lines. If you want metacharacters to match newlines, you'll need to use the /s modifier.

All this is explained in perlre, which is part of the standard on-line help that accompanies Perl. If you're using ActiveState, it's in the on-line Perl documentation that you can find via   Start | Programs | ActiveState ActivePerl | Documentation If you're on *nix, type perldoc perlre at your favorite shell prompt.