php 检查端口是否被占用

$ip='127.0.0.1';
$port=9888;
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_set_nonblock($sock);
socket_connect($sock,$ip, $port);
socket_set_block($sock);
$return = @socket_select($r = array($sock), $w = array($sock), $f = array($sock), 3);
socket_close($sock);
if($return==2){
shell_exec("sudo fuser -k -n tcp 9888");
shell_exec('php webserver.php');
}
var_dump($return);