(PHP 4 >= 4.1.0, PHP 5, PHP 7)
socket_shutdown — Shuts down a socket for receiving, sending, or both
$socket
   [, int $how = 2
  ] ) : bool
   The socket_shutdown() function allows you to stop
   incoming, outgoing or all data (the default) from being sent through the
   socket
  
Note:
The associated buffer, or buffers, may or may not be emptied.
socketA valid socket resource created with socket_create().
how
       The value of how can be one of the following:
       
0 | 
           Shutdown socket reading | 
1 | 
           Shutdown socket writing | 
2 | 
           Shutdown socket reading and writing | 
   成功时返回 TRUE, 或者在失败时返回 FALSE。