sys_un.h(7POSIX) POSIX Programmer's Manual sys_un.h(7POSIX)
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 func‐
tions.
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).
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 discrep‐
ancy 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 .
IEEE/The Open Group 2013 sys_un.h(7POSIX)