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'\" te
.\" Copyright (c) 2002, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 1989 AT&T
.\" Portions Copyright (c) 2001, the Institute of Electrical and Electronics Engineers, Inc. and The Open Group. All Rights Reserved.
.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at
.\" http://www.opengroup.org/bookstore/.
.\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.
.\" This notice shall appear on any product containing this material.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH PIPE 2 "Apr 23, 2002"
.SH NAME
pipe \- create an interprocess channel
.SH SYNOPSIS
.LP
.nf
#include <unistd.h>
\fBint\fR \fBpipe\fR(\fBint\fR \fIfildes\fR[2]);
.fi
.SH DESCRIPTION
.sp
.LP
The \fBpipe()\fR function creates an I/O mechanism called a pipe and returns
two file descriptors, \fIfildes\fR[\fB0\fR] and \fIfildes\fR[\fB1\fR]. The
files associated with \fIfildes\fR[\fB0\fR] and \fIfildes\fR[\fB1\fR] are
streams and are both opened for reading and writing. The \fBO_NDELAY\fR,
\fBO_NONBLOCK\fR, and \fBFD_CLOEXEC\fR flags are cleared on both file
descriptors. The \fBfcntl\fR(2) function can be used to set these flags.
.sp
.LP
A read from \fIfildes\fR[\fB0\fR] accesses the data written to
\fIfildes\fR[\fB1\fR] on a first-in-first-out (FIFO) basis and a read from
\fIfildes\fR[\fB1\fR] accesses the data written to \fIfildes\fR[\fB0\fR] also
on a \fBFIFO\fR basis.
.sp
.LP
Upon successful completion \fBpipe()\fR marks for update the \fBst_atime\fR,
\fBst_ctime\fR, and \fBst_mtime\fR fields of the pipe.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fB0\fR is returned. Otherwise, \fB\(mi1\fR is
returned and \fBerrno\fR is set to indicate the error.
.SH ERRORS
.sp
.LP
The \fBpipe()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEMFILE\fR\fR
.ad
.RS 10n
More than {\fBOPEN_MAX\fR} file descriptors are already in use by this process.
.RE
.sp
.ne 2
.na
\fB\fBENFILE\fR\fR
.ad
.RS 10n
The number of simultaneously open files in the system would exceed a
system-imposed limit.
.RE
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp
.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE ATTRIBUTE VALUE
_
Interface Stability Standard
_
MT-Level Async-Signal-Safe
.TE
.SH SEE ALSO
.sp
.LP
\fBsh\fR(1), \fBfcntl\fR(2), \fBfstat\fR(2), \fBgetmsg\fR(2), \fBpoll\fR(2),
\fBputmsg\fR(2), \fBread\fR(2), \fBwrite\fR(2), \fBattributes\fR(5),
\fBstandards\fR(5), \fBstreamio\fR(7I)
.SH NOTES
.sp
.LP
Since a pipe is bi-directional, there are two separate flows of data.
Therefore, the size (\fBst_size\fR) returned by a call to \fBfstat\fR(2) with
argument \fIfildes\fR[\fB0\fR] or \fIfildes\fR[\fB1\fR] is the number of bytes
available for reading from \fIfildes\fR[\fB0\fR] or \fIfildes\fR[\fB1\fR]
respectively. Previously, the size (\fBst_size\fR) returned by a call to
\fBfstat()\fR with argument \fIfildes\fR[\fB1\fR] (the write-end) was the
number of bytes available for reading from \fIfildes\fR[\fB0\fR] (the
read-end).
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