php socket编程

$socket = @socket_create_listen("55555") or die("Failed to create socket !\n");
while(true){
    $client = socket_accept($socket);
    socket_write($client,"欢迎");
    while(true){
        $input = trim(socket_read($client,256));
        if($input == ‘!exit‘) break;
        if($input == ‘!die‘){
            socket_close($client); break 2;
        }
        $output = strtoupper($input).‘\n‘;
        socket_write($client,$output);
        echo $input.‘\n‘;
    }
    socket_close($client);
}
socket_close($socket);