Understanding flock()

Im trying to simulate conditions, to see how flock works. Can anyone verify with the example code below, that data, never gets written to the file. //1 & //2 are supposed to be processes??? For me, the var_dump() reports -> int(7) bool(false) Thanks $fp = fopen('foo.txt', 'w'); //1 flock($fp, LOCK_EX) or die('Unable to lock'); //1 unlink('foo.txt') or die('Unable to remove foo.txt'); //2 $bytes = fwrite($fp, 'testing'); //1 fclose($fp); //1 var_dump($bytes, file_get_contents('foo.txt')); //1