Well, if you don't have anything in the if block, why not put everything in the one if test? The following is a cleaner example (IMHO) and I've used character classes because they tend to be more efficient than the the /i modifier (they work here only because you had simple regexes). Also, I broke the regexes out into separate tests rather than use the inefficient alternations.

#see if it hasn't been touched in 3 days 
if (-M "$logdir/$f" > 3.0                             and
     #see if file begins with ab or def
     ( $f =~ /^[Aa][Bb]/ or $f =~ /^[Dd][Ee][Ff]/ )   and
     #see if hasn't been zipped already 
     ! ($f =~ /gz\b/ ) ) {
         system ("/usr/local/bin/gzip", "$logdir/$f");
}
[download]

Cheers,
Ovid

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