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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 .