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23 <script language="JavaScript" src="../jscript/codes.js"></script><basefont size="3">
24 <center><font size="2">The Open Group Base Specifications Issue 8<br>
25 IEEE Std 1003.1-2024<br>
26 Copyright © 2001-2024 The IEEE and The Open Group</font></center>
27 <hr size="2" noshade>
28 <a name="top" id="top"></a> <a name="basename" id="basename"></a> <a name="tag_20_07" id="tag_20_07"></a><!-- basename -->
29 <h4 class="mansect"><a name="tag_20_07_01" id="tag_20_07_01"></a>NAME</h4>
30 <blockquote>basename — return non-directory portion of a pathname</blockquote>
31 <h4 class="mansect"><a name="tag_20_07_02" id="tag_20_07_02"></a>SYNOPSIS</h4>
32 <blockquote class="synopsis">
33 <p><code><tt>basename</tt> <i>string</i> <b>[</b><i>suffix</i><b>]</b></code></p>
34 </blockquote>
35 <h4 class="mansect"><a name="tag_20_07_03" id="tag_20_07_03"></a>DESCRIPTION</h4>
36 <blockquote>
37 <p>The <i>string</i> operand shall be treated as a pathname, as defined in XBD <a href=
38 "../basedefs/V1_chap03.html#tag_03_254"><i>3.254 Pathname</i></a> . The string <i>string</i> shall be converted to the filename
39 corresponding to the last pathname component in <i>string</i> and then the suffix string <i>suffix</i>, if present, shall be
40 removed. This shall be done by performing actions equivalent to the following steps in order:</p>
41 <ol>
42 <li>
43 <p>If <i>string</i> is a null string, it is unspecified whether the resulting string is <tt>'.'</tt> or a null string. In either
44 case, skip steps 2 through 6.</p>
45 </li>
46 <li>
47 <p>If <i>string</i> is <tt>"//"</tt>, it is implementation-defined whether steps 3 to 6 are skipped or processed.</p>
48 </li>
49 <li>
50 <p>If <i>string</i> consists entirely of <slash> characters, <i>string</i> shall be set to a single <slash> character.
51 In this case, skip steps 4 to 6.</p>
52 </li>
53 <li>
54 <p>If there are any trailing <slash> characters in <i>string</i>, they shall be removed.</p>
55 </li>
56 <li>
57 <p>If there are any <slash> characters remaining in <i>string</i>, the prefix of <i>string</i> up to and including the last
58 <slash> character in <i>string</i> shall be removed.</p>
59 </li>
60 <li>
61 <p>If the <i>suffix</i> operand is present, is not identical to the characters remaining in <i>string</i>, and is identical to a
62 suffix of the characters remaining in <i>string</i>, the suffix <i>suffix</i> shall be removed from <i>string</i>. Otherwise,
63 <i>string</i> is not modified by this step. It shall not be considered an error if <i>suffix</i> is not found in <i>string</i>.</p>
64 </li>
65 </ol>
66 <p>The resulting string shall be written to standard output.</p>
67 </blockquote>
68 <h4 class="mansect"><a name="tag_20_07_04" id="tag_20_07_04"></a>OPTIONS</h4>
69 <blockquote>
70 <p>None.</p>
71 </blockquote>
72 <h4 class="mansect"><a name="tag_20_07_05" id="tag_20_07_05"></a>OPERANDS</h4>
73 <blockquote>
74 <p>The following operands shall be supported:</p>
75 <dl compact>
76 <dd></dd>
77 <dt><i>string</i></dt>
78 <dd>A string.</dd>
79 <dt><i>suffix</i></dt>
80 <dd>A string.</dd>
81 </dl>
82 </blockquote>
83 <h4 class="mansect"><a name="tag_20_07_06" id="tag_20_07_06"></a>STDIN</h4>
84 <blockquote>
85 <p>Not used.</p>
86 </blockquote>
87 <h4 class="mansect"><a name="tag_20_07_07" id="tag_20_07_07"></a>INPUT FILES</h4>
88 <blockquote>
89 <p>None.</p>
90 </blockquote>
91 <h4 class="mansect"><a name="tag_20_07_08" id="tag_20_07_08"></a>ENVIRONMENT VARIABLES</h4>
92 <blockquote>
93 <p>The following environment variables shall affect the execution of <i>basename</i>:</p>
94 <dl compact>
95 <dd></dd>
96 <dt><i>LANG</i></dt>
97 <dd>Provide a default value for the internationalization variables that are unset or null. (See XBD <a href=
98 "../basedefs/V1_chap08.html#tag_08_02"><i>8.2 Internationalization Variables</i></a> for the precedence of internationalization
99 variables used to determine the values of locale categories.)</dd>
100 <dt><i>LC_ALL</i></dt>
101 <dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
102 <dt><i>LC_CTYPE</i></dt>
103 <dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
104 opposed to multi-byte characters in arguments).</dd>
105 <dt><i>LC_MESSAGES</i></dt>
106 <dd><br>
107 Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.</dd>
108 <dt><i>NLSPATH</i></dt>
109 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
110 Determine the location of messages objects and message catalogs. <img src="../images/opt-end.gif" alt="[Option End]" border=
111 "0"></dd>
112 </dl>
113 </blockquote>
114 <h4 class="mansect"><a name="tag_20_07_09" id="tag_20_07_09"></a>ASYNCHRONOUS EVENTS</h4>
115 <blockquote>
116 <p>Default.</p>
117 </blockquote>
118 <h4 class="mansect"><a name="tag_20_07_10" id="tag_20_07_10"></a>STDOUT</h4>
119 <blockquote>
120 <p>The <i>basename</i> utility shall write a line to the standard output in the following format:</p>
121 <pre>
122 <tt>"%s\n", <</tt><i>resulting string</i><tt>>
123 </tt></pre></blockquote>
124 <h4 class="mansect"><a name="tag_20_07_11" id="tag_20_07_11"></a>STDERR</h4>
125 <blockquote>
126 <p>The standard error shall be used only for diagnostic messages.</p>
127 </blockquote>
128 <h4 class="mansect"><a name="tag_20_07_12" id="tag_20_07_12"></a>OUTPUT FILES</h4>
129 <blockquote>
130 <p>None.</p>
131 </blockquote>
132 <h4 class="mansect"><a name="tag_20_07_13" id="tag_20_07_13"></a>EXTENDED DESCRIPTION</h4>
133 <blockquote>
134 <p>None.</p>
135 </blockquote>
136 <h4 class="mansect"><a name="tag_20_07_14" id="tag_20_07_14"></a>EXIT STATUS</h4>
137 <blockquote>
138 <p>The following exit values shall be returned:</p>
139 <dl compact>
140 <dd></dd>
141 <dt> 0</dt>
142 <dd>Successful completion.</dd>
143 <dt>>0</dt>
144 <dd>An error occurred.</dd>
145 </dl>
146 </blockquote>
147 <h4 class="mansect"><a name="tag_20_07_15" id="tag_20_07_15"></a>CONSEQUENCES OF ERRORS</h4>
148 <blockquote>
149 <p>Default.</p>
150 </blockquote>
151 <hr>
152 <div class="box"><em>The following sections are informative.</em></div>
153 <h4 class="mansect"><a name="tag_20_07_16" id="tag_20_07_16"></a>APPLICATION USAGE</h4>
154 <blockquote>
155 <p>The definition of <i>pathname</i> specifies implementation-defined behavior for pathnames starting with two <slash>
156 characters. Therefore, applications shall not arbitrarily add <slash> characters to the beginning of a pathname unless they
157 can ensure that there are more or less than two or are prepared to deal with the implementation-defined consequences.</p>
158 </blockquote>
159 <h4 class="mansect"><a name="tag_20_07_17" id="tag_20_07_17"></a>EXAMPLES</h4>
160 <blockquote>
161 <p>If the string <i>string</i> is a valid pathname:</p>
162 <pre>
163 <tt>$(basename -- "</tt><i>string</i><tt>")
164 </tt></pre>
165 <p>produces a filename that could be used to open the file named by <i>string</i> in the directory returned by:</p>
166 <pre>
167 <tt>$(dirname -- "</tt><i>string</i><tt>")
168 </tt></pre>
169 <p>If the string <i>string</i> is not a valid pathname, the same algorithm is used, but the result need not be a valid filename.
170 The <i>basename</i> utility is not expected to make any judgements about the validity of <i>string</i> as a pathname; it just
171 follows the specified algorithm to produce a result string.</p>
172 <p>The following shell script compiles <b>/usr/src/cmd/cat.c</b> and moves the output to a file named <b>cat</b> in the current
173 directory when invoked with the argument <b>/usr/src/cmd/cat</b> or with the argument <b>/usr/src/cmd/cat.c</b>:</p>
174 <pre>
175 <tt>c17 -- "$(dirname -- "$1")/$(basename -- "$1" .c).c" &&
176 mv a.out "$(basename -- "$1" .c)"
177 </tt></pre>
178 <p>The EXAMPLES section of the <a href="../functions/basename.html"><i>basename</i>()</a> function (see XSH <a href=
179 "../functions/basename.html#tag_17_42"><i>basename</i></a> ) includes a table showing examples of the results of processing several
180 sample pathnames by the <a href="../functions/basename.html"><i>basename</i>()</a> and <a href=
181 "../functions/dirname.html"><i>dirname</i>()</a> functions and by the <i>basename</i> and <a href=
182 "../utilities/dirname.html"><i>dirname</i></a> utilities.</p>
183 </blockquote>
184 <h4 class="mansect"><a name="tag_20_07_18" id="tag_20_07_18"></a>RATIONALE</h4>
185 <blockquote>
186 <p>The behaviors of <i>basename</i> and <a href="../utilities/dirname.html"><i>dirname</i></a> have been coordinated so that when
187 <i>string</i> is a valid pathname:</p>
188 <pre>
189 <tt>$(basename -- "</tt><i>string</i><tt>")
190 </tt></pre>
191 <p>would be a valid filename for the file in the directory:</p>
192 <pre>
193 <tt>$(dirname -- "</tt><i>string</i><tt>")
194 </tt></pre>
195 <p>This would not work for the early proposal versions of these utilities due to the way it specified handling of trailing
196 <slash> characters.</p>
197 <p>Since the definition of <i>pathname</i> specifies implementation-defined behavior for pathnames starting with two <slash>
198 characters, this volume of POSIX.1-2024 specifies similar implementation-defined behavior for the <i>basename</i> and <a href=
199 "../utilities/dirname.html"><i>dirname</i></a> utilities.</p>
200 </blockquote>
201 <h4 class="mansect"><a name="tag_20_07_19" id="tag_20_07_19"></a>FUTURE DIRECTIONS</h4>
202 <blockquote>
203 <p>If this utility is directed to display a pathname that contains any bytes that have the encoded value of a <newline>
204 character when <newline> is a terminator or separator in the output format being used, implementations are encouraged to
205 treat this as an error. A future version of this standard may require implementations to treat this as an error.</p>
206 </blockquote>
207 <h4 class="mansect"><a name="tag_20_07_20" id="tag_20_07_20"></a>SEE ALSO</h4>
208 <blockquote>
209 <p><a href="../utilities/V3_chap02.html#tag_19_05"><i>2.5 Parameters and Variables</i></a> , <a href=
210 "../utilities/dirname.html#tag_20_35"><i>dirname</i></a></p>
211 <p>XBD <a href="../basedefs/V1_chap03.html#tag_03_254"><i>3.254 Pathname</i></a> , <a href=
212 "../basedefs/V1_chap08.html#tag_08"><i>8. Environment Variables</i></a></p>
213 <p>XSH <a href="../functions/basename.html#tag_17_42"><i>basename</i></a> , <a href=
214 "../functions/dirname.html#tag_17_108"><i>dirname</i></a></p>
215 </blockquote>
216 <h4 class="mansect"><a name="tag_20_07_21" id="tag_20_07_21"></a>CHANGE HISTORY</h4>
217 <blockquote>
218 <p>First released in Issue 2.</p>
219 </blockquote>
220 <h4 class="mansect"><a name="tag_20_07_22" id="tag_20_07_22"></a>Issue 6</h4>
221 <blockquote>
222 <p>IEEE PASC Interpretation 1003.2 #164 is applied.</p>
223 <p>The normative text is reworded to avoid use of the term "must" for application requirements.</p>
224 </blockquote>
225 <h4 class="mansect"><a name="tag_20_07_23" id="tag_20_07_23"></a>Issue 7</h4>
226 <blockquote>
227 <p>POSIX.1-2008, Technical Corrigendum 1, XCU/TC1-2008/0065 [192,538], XCU/TC1-2008/0066 [192,538], and XCU/TC1-2008/0067
228 [192,430,538] are applied.</p>
229 <p>POSIX.1-2008, Technical Corrigendum 2, XCU/TC2-2008/0065 [612] is applied.</p>
230 </blockquote>
231 <h4 class="mansect"><a name="tag_20_07_24" id="tag_20_07_24"></a>Issue 8</h4>
232 <blockquote>
233 <p>Austin Group Defect 251 is applied, encouraging implementations to report an error if a utility is directed to display a
234 pathname that contains any bytes that have the encoded value of a <newline> character when <newline> is a terminator or
235 separator in the output format being used.</p>
236 <p>Austin Group Defect 1122 is applied, changing the description of <i>NLSPATH .</i></p>
237 </blockquote>
238 <div class="box"><em>End of informative text.</em></div>
239 <hr>
240 <p> </p>
241 <a href="#top"><span class="topOfPage">return to top of page</span></a><br>
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