As an alternative to sleeping if you are on Linux (or indeed Irix) with FAM installed - you might consider using SGI::FAM which will allow your program to get events when the contents of a directory changes:

          use SGI::FAM;
         my $fam=new SGI::FAM;
         $fam->monitor('foo');
         while (1) {
           my $event=$fam->next_event; # Blocks
           print "Pathname: ", $event->filename,
             " Event: ", $event->type, "\n";
         }
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This will report every time a new file is created in the 'foo' directory.

/J\