Looking in the File::MMagic source, I see this (edited for relevance):

use vars qw( $dataLoc );

sub new{
  $dataLoc = $fh->tell() if (! defined $dataLoc);
}
[download]

Question: since $dataLoc is a package-scope variable and will only be initialized once, would this cause problems when forked?

I wrote some quick and dirty sample code which does, indeed go wrong if I use File::MMagic. I assume Anonymous Monk is using use. If I require File::MMagic after the fork, it seems to work fine.

So, question to Monks-more-experienced-than-I: What happens to package variables when you fork?

Russ
Brainbench 'Most Valuable Professional' for Perl