Access to a server process after start command

I want to create a php server. I made a command to start the server asynchronously. I would like to place an order to stop the server. I can not get the process after running the start command.

Run Command

$server = new Server();
$pid = pcntl_fork();
if ($pid > 0) {
    echo "Server Runned";
    return;
}
$server->Run();

Server Class

class Server {
    private $_loop;
    private $_socket;

    public function __construct() {
        $this->_loop = Factory::create();
        $this->_socket = new ReactServer($this->_loop );
        $this->_socket->on(
            'connection',function ($conn) {
                echo "Connection";
            } 
        );
    }

    public static function Stop () {
        $this->_loop-> stop();
    }
    public function Run () {
        $this->_loop->run();
    }
}

Thanks for your help !

I have solved my problems.

When i launch my server, i create a file in the tmp directory of system. In my loop, i tcheck if this file is already present. If it was removed, i stop my loop.

So, to stop my server, i can just remove the file.

To can open different server, i name this with host and ports (for exemple : ~/127-0-0-1-8080.pid).

class Loop
{
    private $lockFile;

    public static function getLockFile($address)
    {
        return sys_get_temp_dir().'/'.strtr($address, '.:', '--').'.pid';
    }

    public function __construct($address)
    {
        $this->lockFile = Loop::getLockFile($address);
        touch($this->lockFile);
        //...
    }
    public function run()
    {
        $this->running = true;
        while ($this->running) {

            if (!file_exists($this->lockFile)) {
                $this->running = false;
                echo "File Removed";
            }
            //...
        }
    }
    public function stop()
    {
        $this->running = false;
        unlink($this->lockFile);
    }

}

Start Command :

$server = new Server($em, $port, $host);
$pid = pcntl_fork();
if ($pid > 0) {
   $address = $host.":".$port;
   echo "Server Starting " . $adresse;
}
$server->Run();

Stop Command :

$host = '127.0.0.1';
$port = 5821;
$lockFile = Loop::getLockFile($host.":".$port);
unlink($lockFile);
echo "Server Stopped";