SOCKETPAIR(2)		   Linux Programmer's Manual		 SOCKETPAIR(2)



NAME
       socketpair - create a pair of connected sockets

SYNOPSIS
       #include <sys/types.h>	       /* See NOTES */
       #include <sys/socket.h>

       int socketpair(int domain, int type, int protocol, int sv[2]);

DESCRIPTION
       The  socketpair()  call creates an unnamed pair of connected sockets in
       the specified domain, of the specified type, and using  the  optionally
       specified  protocol.   For  further  details  of	 these	arguments, see
       socket(2).

       The file descriptors used in referencing the new sockets	 are  returned
       in sv[0] and sv[1].  The two sockets are indistinguishable.

RETURN VALUE
       On  success,  zero is returned.	On error, -1 is returned, and errno is
       set appropriately.

       On Linux (and other systems), socketpair() does not modify sv on	 fail-
       ure.    A   requirement	 standardizing	this  behavior	was  added  in
       POSIX.1-2016.

ERRORS
       EAFNOSUPPORT
	      The specified address family is not supported on this machine.

       EFAULT The address sv does not specify a	 valid	part  of  the  process
	      address space.

       EMFILE The per-process limit on the number of open file descriptors has
	      been reached.

       ENFILE The system-wide limit on the total number of open files has been
	      reached.

       EOPNOTSUPP
	      The  specified  protocol	does  not  support  creation of socket
	      pairs.

       EPROTONOSUPPORT
	      The specified protocol is not supported on this machine.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, 4.4BSD.   socketpair()  first  appeared  in
       4.2BSD.	 It  is	 generally portable to/from non-BSD systems supporting
       clones of the BSD socket layer (including System V variants).

NOTES
       On Linux, the only supported domain for this call is AF_UNIX  (or  syn-
       onymously,  AF_LOCAL).	(Most  implementations	have the same restric-
       tion.)

       Since  Linux  2.6.27,  socketpair()  supports  the  SOCK_NONBLOCK   and
       SOCK_CLOEXEC flags in the type argument, as described in socket(2).

       POSIX.1	does  not  require  the	 inclusion  of <sys/types.h>, and this
       header file is not required on Linux.  However, some  historical	 (BSD)
       implementations	required  this	header file, and portable applications
       are probably wise to include it.

SEE ALSO
       pipe(2), read(2), socket(2), write(2), socket(7), unix(7)

COLOPHON
       This page is part of release 4.10 of the Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2016-03-15			 SOCKETPAIR(2)