sys_un.h(0p) — Linux manual page

sys_un.h(0P)            POSIX Programmer's Manual           sys_un.h(0P)

PROLOG         top

       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         top

       sys/un.h — definitions for UNIX domain sockets

SYNOPSIS         top

       #include <sys/un.h>

DESCRIPTION         top

       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         top

       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).

       Although applications are required to initialize all members
       (including any non-standard ones) of a sockaddr_in6 structure
       (see netinet_in.h(0p)), the same is not required for the
       sockaddr_un structure, since historically many applications only
       initialized the standard members. Despite this, applications are
       encouraged to initialize sockaddr_un structures in a manner
       similar to the required initialization of sockaddr_in6
       structures.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       netinet_in.h(0p), sys_socket.h(0p)

       The System Interfaces volume of POSIX.1‐2017, bind(3p),
       socket(3p), socketpair(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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 .

IEEE/The Open Group               2017                      sys_un.h(0P)

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