Manual page for pipe(2)
pipe - create an interprocess channel
SYNOPSIS
#include <unistd.h>
int pipe(int fildes[2]);
MT-LEVEL
Async-Signal-Safe
DESCRIPTION
pipe()
creates an I/O mechanism called a pipe and returns two file descriptors,
fildes[0]
and
fildes[1].
The files associated with fildes[0] and fildes[1] are
streams and are both opened for reading and writing.
The O_NDELAY and O_NONBLOCK flags are cleared.
A read from fildes[0] accesses the data written to fildes[1]
on a first-in-first-out (FIFO) basis and a read from fildes[1]
accesses the data written to fildes[0] also on a FIFO basis.
The FD_CLOEXEC flag will be clear on both file descriptors.
Upon successful completion
pipe()
marks for update the
st_atime, st_ctime, and st_mtime fields of the pipe.
RETURN VALUES
Upon successful completion,
a value of 0 is returned.
Otherwise, a value of -1 is returned and
errno is set to indicate the error.
ERRORS
pipe()
fails if:
- EMFILE
-
If {OPEN_MAX}-1 or more file descriptors are currently open for this process.
- ENFILE
-
A file table entry could not be allocated.
SEE ALSO
sh.1
fcntl.2
getmsg.2
poll.2
putmsg.2
read.2
write.2
streamio.7i
NOTES
Since a pipe is bi-directional, there are two separate flows of data.
Therefore, the size (st_size) returned by a call to
fstat ()
with argument
fildes[0] or
fildes[1]
is the number of bytes available for reading from
fildes[0] or
fildes[1]
respectively.
Previously, the size
(st_size) returned by a call to
fstat()
with argument
fildes[1]
(the write-end) was the number of bytes available for reading from
fildes[0] (the read-end).
Created by unroff & hp-tools.
© by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97
