use DB_File;
tie %ages, 'DB_File', $age_database, O_CREAT|O_RDWR, 0700;
sub test_new {
  my ($mydir) = @_;
  my $new_one = 0;
  opendir(DIR, $mydir) or die("...");
  while (my $file = readdir(DIR)) {
    next if $file !~ /^\.+$/;
    my $mtime = (stat($file))[9];
    next if $mtime == $ages{$file};
    $ages{$file} = $mtime;
    #the $file is new! Process it any way you like
    $new_one = 1;
  }
  closedir(DIR);
  return $new_one;
}