PIPE(2) BSD System Calls Manual PIPE(2)NAMEpipe — 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 descrip‐
tor 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 ALSOsh(1), fork(2), read(2), socketpair(2), fcntl(2), write(2)HISTORY
A pipe() function call appeared in Version 6 AT&T UNIX.
4th Berkeley Distribution February 17, 2011 4th Berkeley Distribution
