📄 fileno.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>fileno</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="fileno"></a> <a name="tag_03_167"></a><!-- fileno --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_167_01"></a>NAME</h4><blockquote>fileno - map a stream pointer to a file descriptor</blockquote><h4><a name="tag_03_167_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/stdio.h.html">stdio.h</a>><br><br> int fileno(FILE *</tt><i>stream</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_167_03"></a>DESCRIPTION</h4><blockquote><p>The <i>fileno</i>() function shall return the integer file descriptor associated with the stream pointed to by<i>stream</i>.</p></blockquote><h4><a name="tag_03_167_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, <i>fileno</i>() shall return the integer value of the file descriptor associated with <i>stream</i>.Otherwise, the value -1 shall be returned and <i>errno</i> set to indicate the error.</p></blockquote><h4><a name="tag_03_167_05"></a>ERRORS</h4><blockquote><p>The <i>fileno</i>() function may fail if:</p><dl compact><dt>[EBADF]</dt><dd>The <i>stream</i> argument is not a valid stream.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_167_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_167_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_167_08"></a>RATIONALE</h4><blockquote><p>Without some specification of which file descriptors are associated with these streams, it is impossible for an application toset up the streams for another application it starts with <a href="../functions/fork.html"><i>fork</i>()</a> and <i><a href="../functions/exec.html">exec</a></i>. In particular, it would not be possible to write a portable version of the <a href="../utilities/sh.html"><i>sh</i></a> command interpreter (although there may be other constraints that would prevent thatportability).</p></blockquote><h4><a name="tag_03_167_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_167_10"></a>SEE ALSO</h4><blockquote><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="fdopen.html"><i>fdopen</i>()</a> , <a href="fopen.html"><i>fopen</i>()</a> , <a href="stdin.html"><i>stdin</i>()</a> , the BaseDefinitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a></p></blockquote><h4><a name="tag_03_167_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_167_12"></a>Issue 6</h4><blockquote><p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p><ul><li><p>The [EBADF] optional error condition is added.</p></li></ul></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -