Be aware that the script as written will only work correctly if it's in the same directory as the files to be processed.

When using opendir/readdir only the file names are being returned, not the full path. If the script is in some other directory, then your open call will fail because it lacks the required path to the file and will die at that point without ever parsing any files.

You should either include $directory in the open call, or add it to $file prior to the open call, or use the glob function to retrieve the file list.