'\" 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. .TH pipe 2 "23 Apr 2002" "SunOS 5.11" "System Calls" .SH NAME pipe \- create an interprocess channel .SH SYNOPSIS .LP .nf #include \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 .mk .na \fB\fBEMFILE\fR\fR .ad .RS 10n .rt More than {\fBOPEN_MAX\fR} file descriptors are already in use by this process. .RE .sp .ne 2 .mk .na \fB\fBENFILE\fR\fR .ad .RS 10n .rt 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 tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) . ATTRIBUTE TYPEATTRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelAsync-Signal-Safe _ StandardSee \fBstandards\fR(5). .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).