if ( $oldfiles{$shortenedname}++  ) {
          my $base = substr($file, 0, 6);
          my $test_shortenedname = 'not found';
          for my $i ( 1 .. 9, a .. z ) {
             $test_shortenedname = $base . '~' . $i;
                 unless $oldfiles{$test_shortenedname};
          }
          next if ($test_shortenedname eq 'not found');
# rather than die, just skip the bad/unshortenable name
          $shortenedname = $test_shortenedname
       }
      push @short_files, $shortenedname;
  }
  return @short_files;