mirror of https://github.com/mkerrisk/man-pages
86 lines
2.9 KiB
Plaintext
86 lines
2.9 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "PIPE" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" pipe
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.SH NAME
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pipe \- create an interprocess channel
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.SH SYNOPSIS
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.LP
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\fB#include <unistd.h>
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.br
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.sp
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int pipe(int\fP \fIfildes\fP\fB[2]);
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIpipe\fP() function shall create a pipe and place two file descriptors,
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one each into the arguments \fIfildes\fP[0] and
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\fIfildes\fP[1], that refer to the open file descriptions for the
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read and write ends of the pipe. Their integer values shall be
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the two lowest available at the time of the \fIpipe\fP() call. The
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O_NONBLOCK and FD_CLOEXEC flags shall be clear on both file
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descriptors. (The \fIfcntl\fP() function can be used to set both these
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flags.)
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.LP
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Data can be written to the file descriptor \fIfildes\fP[1] and read
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from the file descriptor \fIfildes\fP[0]. A read on the
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file descriptor \fIfildes\fP[0] shall access data written to the file
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descriptor \fIfildes\fP[1] on a first-in-first-out basis.
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It is unspecified whether \fIfildes\fP[0] is also open for writing
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and whether \fIfildes\fP[1] is also open for reading.
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.LP
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A process has the pipe open for reading (correspondingly writing)
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if it has a file descriptor open that refers to the read end,
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\fIfildes\fP[0] (write end, \fIfildes\fP[1]).
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.LP
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Upon successful completion, \fIpipe\fP() shall mark for update the
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\fIst_atime\fP, \fIst_ctime\fP, and \fIst_mtime\fP fields
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of the pipe.
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.SH RETURN VALUE
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.LP
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Upon successful completion, 0 shall be returned; otherwise, -1 shall
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be returned and \fIerrno\fP set to indicate the error.
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.SH ERRORS
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.LP
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The \fIpipe\fP() function shall fail if:
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.TP 7
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.B EMFILE
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More than {OPEN_MAX} minus two file descriptors are already in use
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by this process.
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.TP 7
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.B ENFILE
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The number of simultaneously open files in the system would exceed
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a system-imposed limit.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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The wording carefully avoids using the verb "to open" in order to
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avoid any implication of use of \fIopen\fP(); see also \fIwrite\fP()
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\&.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIfcntl\fP() , \fIread\fP() , \fIwrite\fP() , the
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Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<fcntl.h>\fP,
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\fI<unistd.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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