Creating a socket (UNIX domain)

Sockets are created with the socket(SSC) call:

s = socket(domain, type, protocol);

Where

domain

The domain is specified as a manifest constant. For the UNIX domain, the constant is always AF_UNIX (address family_UNIX domain). The manifest constants are named AF_whatever because they indicate the ``address family'' to use in interpreting names.

type

Types are:

SOCK_STREAM
SOCK_DGRAM

protocol

For UNIX domain sockets, the protocol must be set to 0. Unlike the Internet domain, the UNIX domain does not allow a choice of protocols. The system returns a small integer descriptor, or handle, to use in later system calls which operate on sockets. This is equivalent to a file descriptor. See open(S).

The socket call also requires the <sys/stdio.h> include file. For example, to create a datagram socket for on-machine use:

   #include <sys/stdio.h>
   

   s = socket(AF_UNIX, SOCK_DGRAM, 0);