Unix Domain: UNIX and UDG
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.
