Exemplos

You can easily extend the first example to handle any number of connections instead of jsut one#!/usr/bin/env php<?phperror_reporting(E_ALL);/* Permitir al script esperar para conexiones. */set_time_limit(0);/* Activar el volcado de salida implícito, así veremos lo que estamo obteniendo * mientras llega. */ob_implicit_flush();$address = '127.0.0.1';$port = 10000;if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) {    echo "socket_create() falló: razón: " . socket_strerror(socket_last_error()) . "\n";}if (socket_bind($sock, $address, $port) === false) {    echo "socket_bind() falló: razón: " . socket_strerror(socket_last_error($sock)) . "\n";}if (socket_listen($sock, 5) === false) {    echo "socket_listen() falló: razón: " . socket_strerror(socket_last_error($sock)) . "\n";}//clients array$clients = array();do {    $read = array();    $read[] = $sock;        $read = array_merge($read,$clients);        // Set up a blocking call to socket_select    if(socket_select($read,$write = NULL, $except = NULL, $tv_sec = 5) < 1)    {        //    SocketServer::debug("Problem blocking socket_select?");        continue;    }        // Handle new Connections    if (in_array($sock, $read)) {                        if (($msgsock = socket_accept($sock)) === false) {            echo "socket_accept() falló: razón: " . socket_strerror(socket_last_error($sock)) . "\n";            break;        }        $clients[] = $msgsock;        $key = array_keys($clients, $msgsock);        /* Enviar instrucciones. */        $msg = "\nBienvenido al Servidor De Prueba de PHP. \n" .        "Usted es el cliente numero: {$key[0]}\n" .        "Para salir, escriba 'quit'. Para cerrar el servidor escriba 'shutdown'.\n";        socket_write($msgsock, $msg, strlen($msg));            }        // Handle Input    foreach ($clients as $key => $client) { // for each client                if (in_array($client, $read)) {            if (false === ($buf = socket_read($client, 2048, PHP_NORMAL_READ))) {                echo "socket_read() falló: razón: " . socket_strerror(socket_last_error($client)) . "\n";                break 2;            }            if (!$buf = trim($buf)) {                continue;            }            if ($buf == 'quit') {                unset($clients[$key]);                socket_close($client);                break;            }            if ($buf == 'shutdown') {                socket_close($client);                break 2;            }            $talkback = "Cliente {$key}: Usted dijo '$buf'.\n";            socket_write($client, $talkback, strlen($talkback));            echo "$buf\n";        }            }        } while (true);socket_close($sock);?>

Good example from Javier.For using in docker container you can use 0 as an address:$address = '0';To broadcast a message to all clients, you can use socket_write() for all required clients:...    // Handle Input    foreach ($clients as $key => $client) {        if (in_array($client, $read)) {            ...            if ($buf == 'message') {                $talkback = "$buf $key\n";                foreach ($clients as $curClient) {                    socket_write($curClient, $talkback, strlen($talkback));                }                continue;            }            ...        }    }...

due to PHP standars modify the code to:<?php//...    $write = NULL;    $except = NULL;    $tv_sec = 5;    // Set up a blocking call to socket_select    if(socket_select($read, $write, $except, $tv_sec) < 1)//...?>