NAME

       sys/un.h - definitions for UNIX domain sockets

SYNOPSIS

       #include <sys/un.h>

DESCRIPTION

       The  <sys/un.h>  header  shall define the sockaddr_un structure that includes at least the
       following members:

              sa_family_t  sun_family  Address family.
              char         sun_path[]  Socket pathname.

       The sockaddr_un structure is used to store addresses for UNIX domain  sockets.  Values  of
       this type shall be cast by applications to struct sockaddr for use with socket functions.

       The sa_family_t type shall be defined as described in <sys/socket.h> .

       The following sections are informative.

APPLICATION USAGE

       The  size  of  sun_path  has intentionally been left undefined.  This is because different
       implementations use different sizes. For example, 4.3 BSD uses a size of 108, and 4.4  BSD
       uses  a  size  of 104. Since most implementations originate from BSD versions, the size is
       typically in the range 92 to 108.

       Applications should not assume a particular length for sun_path or assume that it can hold
       {_POSIX_PATH_MAX} characters (255).

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <sys/socket.h>  ,  the System Interfaces volume of IEEE Std 1003.1-2001, bind(), socket(),
       socketpair()

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .