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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 Too many descriptors are in use by this process.

       ENFILE The system 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

       4.4BSD, POSIX.1-2001.  The socketpair() function call 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
       described in socket(2).

       POSIX.1-2001 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

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