.\"	$NetBSD: socketpair.2,v 1.5 1995/02/27 12:38:00 cgd Exp $
.\"
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.\"     @(#)socketpair.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SOCKETPAIR 2
.Os BSD 4.2
.Sh NAME
.Nm socketpair
.Nd create a pair of connected sockets
.Sh SYNOPSIS
.Fd #include <sys/socket.h>
.Ft int
.Fo socketpair
.Fa "int domain"
.Fa "int type"
.Fa "int protocol"
.Fa "int socket_vector[2]"
.Fc
.Sh DESCRIPTION
The
.Fn socketpair
call creates an unnamed pair of connected sockets in
the specified domain
.Fa domain ,
of the specified
.Fa type ,
and using the optionally specified
.Fa protocol .
The descriptors used in referencing the new sockets
are returned in
.Fa socket_vector Ns [0]
and
.Fa socket_vector Ns [1] .
The two sockets are indistinguishable.
.Sh RETURN VALUES
.Rv -std socketpair
.Sh ERRORS
The call succeeds unless:
.Bl -tag -width Er
.\" ===========
.It Bq Er EAFNOSUPPORT
The specified address family is not supported on this machine.
.\" ===========
.It Bq Er EFAULT
The address
.Fa socket_vector
does not specify a valid part of the process address space.
.\" ===========
.It Bq Er EMFILE
No more file descriptors are available for this process.
.\" ===========
.It Bq Er ENFILE
No more file descriptors are available for the system.
.\" ===========
.It Bq Er ENOBUFS
Insufficient resources were available in the system
to perform the operation.
.\" ===========
.It Bq Er ENOMEM
Insufficient memory was available to fulfill the request.
.\" ===========
.It Bq Er EOPNOTSUPP
The specified protocol does not support creation of socket pairs.
.\" ===========
.It Bq Er EPROTONOSUPPORT
The specified protocol is not supported on this machine.
.\" ===========
.It Bq Er EPROTOTYPE
The socket type is not supported by the protocol.
.\" ===========
.It Bq Er EACCES
The process does not have appropriate privileges to create a socket of the 
specified type and/or protocol.
.El
.Sh LEGACY SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <sys/socket.h>
.Pp
The include file
.In sys/types.h
is necessary.
.Sh SEE ALSO
.Xr socket 2 ,
.Xr read 2 ,
.Xr write 2 ,
.Xr compat 5
.Sh BUGS
This call is currently implemented only for the
.Tn UNIX
domain.
.Sh HISTORY
The
.Fn socketpair
function call appeared in
.Bx 4.2 .