sub create_link($) {
	my $fh = shift(@_);
	my $max = 10;
	my $err = '';
	sysopen($fh, "sysopentest.txt",O_RDWR|O_CREAT,0600) or $err=$!;
	if (!$err) {
		my $start = time;
		my $flock = flock($fh,LOCK_EX|LOCK_NB);
		while (!$flock && time-$start < $max) {
print "Flock: >$flock< warte 1\n";
			sleep 1;
			$flock = flock($fh,LOCK_EX|LOCK_NB);
		}
		$err = 'Timeout on flock' if !$flock;
	}
	return $err;
}