136 lines
4.4 KiB
HTML
136 lines
4.4 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta name="generator" content="HTML Tidy, see www.w3.org">
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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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>fileno</title>
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</head>
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<body bgcolor="white">
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<script type="text/javascript" language="JavaScript" src="../jscript/codes.js">
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</script>
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<basefont size="3"> <a name="fileno"></a> <a name="tag_03_167"></a><!-- fileno -->
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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_167_01"></a>NAME</h4>
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<blockquote>fileno - map a stream pointer to a file descriptor</blockquote>
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<h4><a name="tag_03_167_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> #include <<a href="../basedefs/stdio.h.html">stdio.h</a>><br>
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<br>
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int fileno(FILE *</tt><i>stream</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div>
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<tt><br>
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</tt></blockquote>
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<h4><a name="tag_03_167_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>fileno</i>() function shall return the integer file descriptor associated with the stream pointed to by
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<i>stream</i>.</p>
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</blockquote>
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<h4><a name="tag_03_167_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>fileno</i>() shall return the integer value of the file descriptor associated with <i>stream</i>.
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Otherwise, the value -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_167_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>fileno</i>() function may fail if:</p>
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<dl compact>
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<dt>[EBADF]</dt>
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<dd>The <i>stream</i> argument is not a valid stream.</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_167_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_167_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_167_08"></a>RATIONALE</h4>
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<blockquote>
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<p>Without some specification of which file descriptors are associated with these streams, it is impossible for an application to
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set up the streams for another application it starts with <a href="../functions/fork.html"><i>fork</i>()</a> and <i><a href=
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"../functions/exec.html">exec</a></i>. In particular, it would not be possible to write a portable version of the <a href=
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"../utilities/sh.html"><i>sh</i></a> command interpreter (although there may be other constraints that would prevent that
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portability).</p>
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</blockquote>
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<h4><a name="tag_03_167_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_167_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="xsh_chap02_05.html#tag_02_05_01"><i>Interaction of File Descriptors and Standard I/O Streams</i></a> , <a href=
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"fdopen.html"><i>fdopen</i>()</a> , <a href="fopen.html"><i>fopen</i>()</a> , <a href="stdin.html"><i>stdin</i>()</a> , the Base
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Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_167_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_167_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 [EBADF] optional error condition is added.</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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POSIX ® is a registered Trademark of The IEEE.<br>
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