pipe(2)pipe(2)Namepipe - create an interprocess channel
Syntax
include <limits.h> /*Definition of PIPE_MAX*/
pipe(fildes)
int fildes[2];
Arguments
fildes Passing an address as an array of two integers into the sys‐
tem call.
Description
The system call creates an I/O mechanism called a pipe. The file
descriptors returned can be used in and operations. Their integer val‐
ues will be the two lowest available at the time of the function call.
The O_NONBLOCK and FD_CLOEXEC flags will be clear on both file descrip‐
tors.
When the pipe is written using the descriptor fildes[1], up to PIPE_MAX
bytes of data are buffered before the writing process is suspended. A
read using the descriptor fildes[0] picks up the data.
It is assumed that after the pipe has been set up, two (or more) coop‐
erating processes (created by subsequent calls) pass data through the
pipe with and calls.
The shell has a syntax to set up a linear array of processes connected
by pipes.
For further information on how and calls behave with pipes, see the and
reference pages.
A signal is generated if a write on a pipe with only one end is
attempted.
Restrictions
Should more than 4096 bytes be necessary in any pipe among a loop of
processes, deadlock may occur.
The underlying implementation of pipes is no longer socket based, but
rather implemented through the file system. Any application that needs
socket functionality from pipes should use the system call.
Return Values
The function value zero is returned if the pipe was created; -1 if an
error occurred.
Diagnostics
The call fails if:
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
[EFAULT] The fildes buffer is in an invalid area of the process's
address space.
Environment
Differs from the System V definition in that ENFILE is not a possible
error condition.
See Alsosh(1), fork(2), read(2), socketpair(2), write(2)pipe(2)
