## Unix Domain: Unix and UDG

`unix://` and `udg://` (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.

> Note: Unix domain sockets are not supported on Windows.