<?php
/* bind to port 11111 on local machine */
$sock stream_socket_server('tcp://localhost:11111');
/* wait for user input */
while ($conn stream_socket_accept($sock)) {
    
$line trim(fgets($conn)); // read user input
    
fwrite($conn"You wrote '$line'\n"); // print response
}
?>
The experimental and rarely available sockets extension is made nearly obsolete.