Predictable filename races

Take this 'better' (but still vulnerable) code:

  if ( not -e $file ) {
      open FILEHANDLE, ">$file";
  }

If symlink pointing to real file is created between test and open, existing file can be overwritten.

Could wipe out important files, or possibly insert useful contents.  (e.g. /etc/hosts.allow)
File could be readable by attacker, providing an idea of what the process does.  (e.g. a log file)
If fchown/fchmod is used, could provide innappropriate access to files.