unix:// since PHP 3, udg:// since PHP 5
unix:///tmp/mysock
udg:///tmp/mysock
unix:// provides access to a socket stream connection in the unix domain. udg:// provides an alternate transport to a unix domain socket using the user datagram protocol.
Unix Domain sockets, unlike Internet Domain sockets, do not expect a port number. In the case of fsockopen() the portno parameter should be set to 0.