close() closes the file (or socket) descriptor given by socket.
Note that close() should not be used on PHP file descriptors created with fopen(), popen(), fsockopen(), or psockopen(); it is meant for sockets created with socket() or accept_connect().
Returns true on success, or false if an error occurs (i.e., socket is invalid).
See also bind(), listen(), socket(), socket_get_status(), and strerror().