---
name: "socketpair"
section: "2"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/socketpair"
---

# socketpair(2)

create a pair of connected sockets

## NAME

socketpair - create a pair of connected sockets

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#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)](/socket/2.md).

The file 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, *errno* is set to indicate the error, and *sv* is left unchanged

On Linux (and other systems), **socketpair**() does not modify *sv* on failure. A requirement standardizing this behavior was added in POSIX.1-2008 TC2.

## 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.

## VERSIONS

On Linux, the only supported domains for this call are **AF\_UNIX** (or synonymously, **AF\_LOCAL**) and **AF\_TIPC** (since Linux 4.12).

## STANDARDS

POSIX.1-2024.

## HISTORY

POSIX.1-2001, 4.2BSD.

It is generally portable to/from non-BSD systems supporting clones of the BSD socket layer (including System V variants).

- **SOCK\_CLOEXEC** **SOCK\_NONBLOCK**

  POSIX.1-2024; Linux 2.6.27. (See [**socket**(2)](/socket/2.md).)

## SEE ALSO

[**pipe**(2)](/pipe/2.md), [**read**(2)](/read/2.md), [**socket**(2)](/socket/2.md), [**write**(2)](/write/2.md), [**socket**(7)](/socket/7.md), [**unix**(7)](/unix/7.md)