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NAME
socketpair - create a pair of connected sockets
SYNOPSIS
#include <sys/types.h>
#include <sys/socket.h>
int socketpair(int d, int type, int protocol, int sv[2]);
DESCRIPTION
The socketpair() call creates an unnamed pair of connected sockets in
the specified domain d, of the specified type, and using the optionally
specified protocol. 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, SUSv2, POSIX 1003.1-2001. 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.)
The header file <sys/types.h> is only required for libc4 or earlier.
Some packages, like util-linux, claim portability to all Linux versions
and libraries. They certainly need this header file.
SEE ALSO
pipe(2), read(2), socket(2), write(2), unix(7)