PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

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, which shall include 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.  Pointers to
       this  type  shall  be  cast  by  applications  to  struct  sockaddr  * for use with socket
       functions.

       The <sys/un.h> header shall define the sa_family_t type 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} bytes (256).

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       <sys_socket.h>

       The System Interfaces volume of POSIX.1‐2008, bind(), socket(), socketpair()

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .