PIPE(2)PIPE(2)NAMEpipe - create an interprocess communication channel
SYNOPSIS
#include <unistd.h>
int pipe(int fildes[2])
DESCRIPTION
The pipe system call creates an I/O mechanism called a pipe. The file
descriptors returned can be used in read and write operations. 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] will pick up the data.
PIPE_MAX equals 7168 under MINIX 3, but note that most systems use
4096.
It is assumed that after the pipe has been set up, two (or more) coop‐
erating processes (created by subsequent fork calls) will pass data
through the pipe with read and write calls.
The shell has a syntax to set up a linear array of processes connected
by pipes.
Read calls on an empty pipe (no buffered data) with only one end (all
write file descriptors closed) returns an end-of-file.
The signal SIGPIPE is generated if a write on a pipe with only one end
is attempted.
RETURN VALUE
The function value zero is returned if the pipe was created; -1 if an
error occurred.
ERRORS
The pipe call will fail if:
[EMFILE] Too many descriptors are active.
[ENFILE] The system file table is full.
[ENOSPC] The pipe file system (usually the root file system) has
no free inodes.
[EFAULT] The fildes buffer is in an invalid area of the process's
address space.
SEE ALSOsh(1), read(2), write(2), fork(2).
NOTES
Writes may return ENOSPC errors if no pipe data can be buffered,
because the pipe file system is full.
BUGS
Should more than PIPE_MAX bytes be necessary in any pipe among a loop
of processes, deadlock will occur.
4th Berkeley Distribution August 26, 1985 PIPE(2)
