---
name: "pipe"
section: "2"
platform: "macos"
package: "xnu"
version: "12377.121.6"
release: "macOS 26.5"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/pipe/2"
---

# pipe(2)

create descriptor pair for interprocess communication

## NAME

**pipe** – create descriptor pair for interprocess communication

## SYNOPSIS

**#include \<unistd.h\>**

*int*\

**pipe**(*int fildes\[2\]*);

## DESCRIPTION

The **pipe**() function creates a *pipe* (an object that allows unidirectional data flow) and allocates a pair of file descriptors. The first descriptor connects to the *read* *end* of the pipe; the second connects to the *write* *end*.

Data written to *fildes\[1\]* appears on (i.e., can be read from) *fildes\[0\]*. This allows the output of one program to be sent to another program: the source's standard output is set up to be the write end of the pipe; the sink's standard input is set up to be the read end of the pipe. The pipe itself persists until all of its associated descriptors are closed.

A pipe whose read or write end has been closed is considered *widowed*. Writing on such a pipe causes the writing process to receive a SIGPIPE signal. Widowing a pipe is the only way to deliver end-of-file to a reader: after the reader consumes any buffered data, reading a widowed pipe returns a zero count.

The generation of the SIGPIPE signal can be suppressed using the F\_SETNOSIGPIPE fcntl command.

## RETURN VALUES

On successful creation of the pipe, zero is returned. Otherwise,  a value of -1 is returned and the variable *errno* set to indicate the error.

## ERRORS

The **pipe**() call will fail if:

- \[EFAULT\]

  The *fildes* buffer is in an invalid area of the process's address space.

- \[EMFILE\]

  Too many descriptors are active.

- \[ENFILE\]

  The system file table is full.

## SEE ALSO

[sh(1)](/sh/1.md), [fork(2)](/fork/2.md), [read(2)](/read/2.md), [socketpair(2)](/socketpair/2.md), [fcntl(2)](/fcntl/2.md), [write(2)](/write/2.md)

## HISTORY

A **pipe**() function call appeared in  Version 6 AT&T UNIX.