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<!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) 2001-2004 IEEE and The Open Group, All Rights Reserved --><title>dirname</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="dirname"></a> <a name="tag_04_38"></a><!-- dirname --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2004 Edition<br>Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_04_38_01"></a>NAME</h4><blockquote>dirname - return the directory portion of a pathname</blockquote><h4><a name="tag_04_38_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>dirname</tt> <i>string</i></code></p></blockquote><h4><a name="tag_04_38_03"></a>DESCRIPTION</h4><blockquote><p>The <i>string</i> operand shall be treated as a pathname, as defined in the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap03.html#tag_03_266">Section 3.266, Pathname</a>. The string<i>string</i> shall be converted to the name of the directory containing the filename corresponding to the last pathname componentin <i>string</i>, performing actions equivalent to the following steps in order:</p><ol><li><p>If <i>string</i> is <b>//</b>, skip steps 2 to 5.</p></li><li><p>If <i>string</i> consists entirely of slash characters, <i>string</i> shall be set to a single slash character. In this case,skip steps 3 to 8.</p></li><li><p>If there are any trailing slash characters in <i>string</i>, they shall be removed.</p></li><li><p>If there are no slash characters remaining in <i>string</i>, <i>string</i> shall be set to a single period character. In thiscase, skip steps 5 to 8.</p></li><li><p>If there are any trailing non-slash characters in <i>string</i>, they shall be removed.</p></li><li><p>If the remaining <i>string</i> is <b>//</b>, it is implementation-defined whether steps 7 and 8 are skipped or processed.</p></li><li><p>If there are any trailing slash characters in <i>string</i>, they shall be removed.</p></li><li><p>If the remaining <i>string</i> is empty, <i>string</i> shall be set to a single slash character.</p></li></ol><p>The resulting string shall be written to standard output.</p></blockquote><h4><a name="tag_04_38_04"></a>OPTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_38_05"></a>OPERANDS</h4><blockquote><p>The following operand shall be supported:</p><dl compact><dt><i>string</i></dt><dd>A string.</dd></dl></blockquote><h4><a name="tag_04_38_06"></a>STDIN</h4><blockquote><p>Not used.</p></blockquote><h4><a name="tag_04_38_07"></a>INPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_38_08"></a>ENVIRONMENT VARIABLES</h4><blockquote><p>The following environment variables shall affect the execution of <i>dirname</i>:</p><dl compact><dt><i>LANG</i></dt><dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> forthe precedence of internationalization variables used to determine the values of locale categories.)</dd><dt><i>LC_ALL</i></dt><dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd><dt><i>LC_CTYPE</i></dt><dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte asopposed to multi-byte characters in arguments).</dd><dt><i>LC_MESSAGES</i></dt><dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standarderror.</dd><dt><i>NLSPATH</i></dt><dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd></dl></blockquote><h4><a name="tag_04_38_09"></a>ASYNCHRONOUS EVENTS</h4><blockquote><p>Default.</p></blockquote><h4><a name="tag_04_38_10"></a>STDOUT</h4><blockquote><p>The <i>dirname</i> utility shall write a line to the standard output in the following format:</p><pre><tt>"%s\n", <</tt><i>resulting string</i><tt>></tt></pre></blockquote><h4><a name="tag_04_38_11"></a>STDERR</h4><blockquote><p>The standard error shall be used only for diagnostic messages.</p></blockquote><h4><a name="tag_04_38_12"></a>OUTPUT FILES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_38_13"></a>EXTENDED DESCRIPTION</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_38_14"></a>EXIT STATUS</h4><blockquote><p>The following exit values shall be returned:</p><dl compact><dt> 0</dt><dd>Successful completion.</dd><dt>>0</dt><dd>An error occurred.</dd></dl></blockquote><h4><a name="tag_04_38_15"></a>CONSEQUENCES OF ERRORS</h4><blockquote><p>Default.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_04_38_16"></a>APPLICATION USAGE</h4><blockquote><p>The definition of <i>pathname</i> specifies implementation-defined behavior for pathnames starting with two slash characters.Therefore, applications shall not arbitrarily add slashes to the beginning of a pathname unless they can ensure that there are moreor less than two or are prepared to deal with the implementation-defined consequences.</p></blockquote><h4><a name="tag_04_38_17"></a>EXAMPLES</h4><blockquote><blockquote><table border="1" cellpadding="3"><tr valign="top"><th align="center"><p class="tent"><b>Command</b></p></th><th align="center"><p class="tent"><b>Results</b></p></th></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> /</p></td><td align="left"><p class="tent">/</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> //</p></td><td align="left"><p class="tent">/ or //</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> /<i>a</i>/<i>b</i>/</p></td><td align="left"><p class="tent">/<i>a</i></p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> //<i>a</i>//<i>b</i>//</p></td><td align="left"><p class="tent">//<i>a</i></p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i></p></td><td align="left"><p class="tent">Unspecified</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname a</i></p></td><td align="left"><p class="tent">. ($? = 0)</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> ""</p></td><td align="left"><p class="tent">. ($? = 0)</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> /<i>a</i></p></td><td align="left"><p class="tent">/</p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> /<i>a</i>/<i>b</i></p></td><td align="left"><p class="tent">/<i>a</i></p></td></tr><tr valign="top"><td align="left"><p class="tent"><i>dirname</i> <i>a</i>/<i>b</i></p></td><td align="left"><p class="tent"><i>a</i></p></td></tr></table></blockquote></blockquote><h4><a name="tag_04_38_18"></a>RATIONALE</h4><blockquote><p>The <i>dirname</i> utility originated in System III. It has evolved through the System V releases to a version that matches therequirements specified in this description in System V Release 3. 4.3 BSD and earlier versions did not include <i>dirname</i>.</p><p>The behaviors of <a href="../utilities/basename.html"><i>basename</i></a> and <i>dirname</i> in this volume ofIEEE Std 1003.1-2001 have been coordinated so that when <i>string</i> is a valid pathname:</p><pre><tt>$(basename "</tt><i>string</i><tt>")</tt></pre><p>would be a valid filename for the file in the directory:</p><pre><tt>$(dirname "</tt><i>string</i><tt>")</tt></pre><p>This would not work for the versions of these utilities in early proposals due to the way processing of trailing slashes wasspecified. Consideration was given to leaving processing unspecified if there were trailing slashes, but this cannot be done; theBase Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap03.html#tag_03_266">Section 3.266,Pathname</a> allows trailing slashes. The <a href="../utilities/basename.html"><i>basename</i></a> and <i>dirname</i> utilitieshave to specify consistent handling for all valid pathnames.</p></blockquote><h4><a name="tag_04_38_19"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_04_38_20"></a>SEE ALSO</h4><blockquote><p><a href="basename.html"><i>basename</i></a>, <a href="xcu_chap02.html#tag_02_05"><i>Parameters and Variables</i></a></p></blockquote><h4><a name="tag_04_38_21"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 2.</p></blockquote><div class="box"><em>End of informative text.</em></div><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
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