1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)socketpair.2 8.1 (Berkeley) 6/4/93 29.\" 30.Dd February 10, 2018 31.Dt SOCKETPAIR 2 32.Os 33.Sh NAME 34.Nm socketpair 35.Nd create a pair of connected sockets 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In sys/types.h 40.In sys/socket.h 41.Ft int 42.Fn socketpair "int domain" "int type" "int protocol" "int *sv" 43.Sh DESCRIPTION 44The 45.Fn socketpair 46system call creates an unnamed pair of connected sockets in 47the specified communications 48.Fa domain , 49of the specified 50.Fa type , 51and using the optionally specified 52.Fa protocol . 53The descriptors used in referencing the new sockets 54are returned in 55.Fa sv Ns [0] 56and 57.Fa sv Ns [1] . 58The two sockets are indistinguishable. 59.Pp 60The 61.Dv SOCK_CLOEXEC 62and 63.Dv SOCK_NONBLOCK 64flags in the 65.Fa type 66argument apply to both descriptors. 67.Sh RETURN VALUES 68.Rv -std socketpair 69.Sh ERRORS 70The call succeeds unless: 71.Bl -tag -width Er 72.It Bq Er EMFILE 73Too many descriptors are in use by this process. 74.It Bq Er EAFNOSUPPORT 75The specified address family is not supported on this machine. 76.It Bq Er EPROTONOSUPPORT 77The specified protocol is not supported on this machine. 78.It Bq Er EOPNOTSUPP 79The specified protocol does not support creation of socket pairs. 80.It Bq Er EFAULT 81The address 82.Fa sv 83does not specify a valid part of the 84process address space. 85.El 86.Sh SEE ALSO 87.Xr pipe 2 , 88.Xr read 2 , 89.Xr socket 2 , 90.Xr write 2 91.Sh STANDARDS 92The 93.Fn socketpair 94system call conforms to 95.St -p1003.1-2001 96and 97.St -p1003.1-2008 . 98.Sh HISTORY 99The 100.Fn socketpair 101system call appeared in 102.Bx 4.2 . 103.Sh BUGS 104This call is currently implemented only for the 105.Ux 106domain. 107