foreach $file (@list_of_files) {
  open FILE, "$dir/$file" || die "Can't open $dir/$file: $!\n";
  while (defined($line = <FILE>)) {
    chomp $line;
    next if ($line =~ /unknown|shutdown/);
    ($name, $ranks, $serial_numbers) = split(' ',$line);
    $HoH{$name}{$ranks} = 1;     
  }
}