use Fcntl qw(:flock);

open(FILE, ">sem.lck") or die $!;
print "Opened file\n";

flock(FILE, LOCK_EX) or die $!;
print "Got lock\n";

sleep(10);

close(FILE);

##</code><code>##

sysopen(FILE, $path, O_RDWR|O_CREAT|O_EXCL) or die $!;