<sys/un.h>(0P)                                      POSIX Programmer's Manual                                     <sys/un.h>(0P)



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 appli-
       cations 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,  Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                <sys/un.h>(0P)