I had to do that recently.

use Time::Local;

my $now   = timelocal(localtime);
my $mtime = (stat $file)[9];
my $delta = ($now - $mtime) / (60 * 60 * 24);
[download]

UPDATE: Corion to the rescue again. :) (That means i learned something too. Yes ... -C works fine, in fact, it works better than fine. I just wish i knew about that last week when i wasted 10 minutes writing that snippet. ;))

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)