UNIX(7F)							      UNIX(7F)

NAME    [Toc]    [Back]

     unix - UNIX-domain	protocol family

SYNOPSIS    [Toc]    [Back]

     #include <sys/types.h>
     #include <sys/un.h>

DESCRIPTION    [Toc]    [Back]

     The UNIX-domain protocol family is	a collection of	protocols that
     provides local (on-machine) interprocess communication through the	normal
     socket(2) mechanisms.  The	UNIX-domain family supports the	SOCK_STREAM
     and SOCK_DGRAM socket types and uses filesystem pathnames for addressing.

ADDRESSING    [Toc]    [Back]

     UNIX-domain addresses are variable-length filesystem pathnames of at most
     108 characters.  The include file <sys/un.h> defines this address:

     struct sockaddr_un	{
	    short     sun_family;
	    char      sun_path[108];
     };

     Binding a name to a UNIX-domain socket with bind(2) causes	a socket file
     to	be created in the filesystem.  This file is not	removed	when the
     socket is closed -	unlink(2) must be used to remove the file.

     The UNIX-domain does not support broadcast	addressing or any form of
     "wildcard"	matching on incoming messages. All addresses are absolute- or
     relative-pathnames	of other UNIX-domain sockets.  Normal filesystem
     access-control mechanisms are also	applied	when referencing pathnames;
     e.g., the destination of a	connect(2) or sendto(2)	must be	writable.

PROTOCOLS    [Toc]    [Back]

     The UNIX-domain protocol family is	comprised of simple transport
     protocols that support the	SOCK_STREAM and	SOCK_DGRAM abstractions.
     SOCK_STREAM sockets also support the communication	of file	descriptors
     through the use of	the msg_accrights field	in the msg argument to
     sendms
.	 Any valid descriptor may be sent in a
     message.  The received descriptor is a duplicate of the sender's
     descriptor, as if it were created with a call to dup(2).  Per-process
     descriptor	flags, set with	fcntl(2), are not passed to a receiver.
     Descriptors that are awaiting delivery, or	that are purposely not
     received, are automatically closed	by the system when the destination
     socket is closed.

DIAGNOSTICS    [Toc]    [Back]

     The bind(2) and connect(2)	socket operations may fail with	one of the
     following errors returned:

     [ENOTDIR]		 A component of	the path prefix	is not a directory.





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UNIX(7F)							      UNIX(7F)



     [ENOENT]		 The named file	does not exist.

     [EACCES]		 Search	permission is denied for a component of	the
			 path prefix.

     [ENAMETOOLONG]	 The length of path exceeds {PATH_MAX},	or a pathname
			 component is longer than {NAME_MAX}.

     [ELOOP]		 Too many symbolic links were encountered in
			 translating the pathname.

SEE ALSO    [Toc]    [Back]

     socket(2),	netintro(7)
     IRIX Network Programming Guide.


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