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 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.

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 synonymously, AF_LOCAL).  (Most
       implementations have the same restriction.)

       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  4.04  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
       http://www.kernel.org/doc/man-pages/.