sub lock {
  my $lockhelper="lockhelper-$ENV{HOSTNAME}-$$.LCK";
  my *LOCK;
  my $nlink;

  open(LOCK, ">$lockhelper") or die "Couldn't open() $lockhelper: $!"; 
  print LOCK "$ENV{HOSTNAME};$$\n";                       
  close(LOCK);
  link($lockhelper, "lockfile.LCK");
  (undef,undef,undef,$nlink,undef,undef,undef,undef,
   undef,undef,undef,undef,undef) = stat($lockhelper);
  unlink($lockhelper);
  return $nlink==2;
}