144 lines
5.0 KiB
HTML
144 lines
5.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 -->
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>pipe</title>
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<body bgcolor="white">
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<basefont size="3"> <a name="pipe"></a> <a name="tag_03_418"></a><!-- pipe -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_418_01"></a>NAME</h4>
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<blockquote>pipe - create an interprocess channel</blockquote>
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<h4><a name="tag_03_418_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/unistd.h.html">unistd.h</a>><br>
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<br>
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int pipe(int</tt> <i>fildes</i><tt>[2]);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_418_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>pipe</i>() function shall create a pipe and place two file descriptors, one each into the arguments <i>fildes</i>[0] and
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<i>fildes</i>[1], that refer to the open file descriptions for the 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 <i>pipe</i>() call. The O_NONBLOCK and FD_CLOEXEC flags shall be clear on both file
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descriptors. (The <a href="../functions/fcntl.html"><i>fcntl</i>()</a> function can be used to set both these flags.)</p>
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<p>Data can be written to the file descriptor <i>fildes</i>[1] and read from the file descriptor <i>fildes</i>[0]. A read on the
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file descriptor <i>fildes</i>[0] shall access data written to the file descriptor <i>fildes</i>[1] on a first-in-first-out basis.
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It is unspecified whether <i>fildes</i>[0] is also open for writing and whether <i>fildes</i>[1] is also open for reading.</p>
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<p>A process has the pipe open for reading (correspondingly writing) if it has a file descriptor open that refers to the read end,
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<i>fildes</i>[0] (write end, <i>fildes</i>[1]).</p>
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<p>Upon successful completion, <i>pipe</i>() shall mark for update the <i>st_atime</i>, <i>st_ctime</i>, and <i>st_mtime</i> fields
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of the pipe.</p>
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</blockquote>
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<h4><a name="tag_03_418_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, 0 shall be returned; otherwise, -1 shall be returned and <i>errno</i> set to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_418_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>pipe</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EMFILE]</dt>
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<dd>More than {OPEN_MAX} minus two file descriptors are already in use by this process.</dd>
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<dt>[ENFILE]</dt>
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<dd>The number of simultaneously open files in the system would exceed a system-imposed limit.</dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_418_06"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_418_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_418_08"></a>RATIONALE</h4>
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<blockquote>
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<p>The wording carefully avoids using the verb "to open" in order to avoid any implication of use of <a href=
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"../functions/open.html"><i>open</i>()</a>; see also <a href="write.html"><i>write</i>()</a> .</p>
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</blockquote>
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<h4><a name="tag_03_418_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_418_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="fcntl.html"><i>fcntl</i>()</a> , <a href="read.html"><i>read</i>()</a> , <a href="write.html"><i>write</i>()</a> , the
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Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/fcntl.h.html"><i><fcntl.h></i></a>, <a href=
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"../basedefs/unistd.h.html"><i><unistd.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_418_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_418_12"></a>Issue 6</h4>
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<blockquote>
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<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
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<ul>
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<li>
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<p>The DESCRIPTION is updated to indicate that certain dispositions of <i>fildes</i>[0] and <i>fildes</i>[1] are unspecified.</p>
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</li>
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</ul>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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