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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="chown" id="chown"></a> <a name="tag_20_18" id="tag_20_18"></a><!-- chown -->
29 <h4 class="mansect"><a name="tag_20_18_01" id="tag_20_18_01"></a>NAME</h4>
30 <blockquote>chown — change the file ownership</blockquote>
31 <h4 class="mansect"><a name="tag_20_18_02" id="tag_20_18_02"></a>SYNOPSIS</h4>
32 <blockquote class="synopsis">
33 <p><code><tt>chown</tt> <b>[</b><tt>-h</tt><b>]</b> <i>owner</i><b>[</b><tt>:</tt><i>group</i><b>]</b> <i>file</i><tt>...<br>
34 <br>
35 chown -R</tt> <b>[</b><tt>-H|-L|-P</tt><b>]</b> <i>owner</i><b>[</b><tt>:</tt><i>group</i><b>]</b> <i>file</i><tt>...<br></tt></code></p>
36 </blockquote>
37 <h4 class="mansect"><a name="tag_20_18_03" id="tag_20_18_03"></a>DESCRIPTION</h4>
38 <blockquote>
39 <p>The <i>chown</i> utility shall set the user ID of the file named by each <i>file</i> operand to the user ID specified by the
40 <i>owner</i> operand.</p>
41 <p>For each <i>file</i> operand, or, if the <b>-R</b> option is used, each file encountered while walking the directory trees
42 specified by the <i>file</i> operands, the <i>chown</i> utility shall perform actions equivalent to the <a href=
43 "../functions/chown.html"><i>chown</i>()</a> function defined in the System Interfaces volume of POSIX.1-2024, called with the
44 following arguments:</p>
45 <ol>
46 <li>
47 <p>The <i>file</i> operand shall be used as the <i>path</i> argument.</p>
48 </li>
49 <li>
50 <p>The user ID indicated by the <i>owner</i> portion of the first operand shall be used as the <i>owner</i> argument.</p>
51 </li>
52 <li>
53 <p>If the <i>group</i> portion of the first operand is given, the group ID indicated by it shall be used as the <i>group</i>
54 argument; otherwise, the group ownership shall not be changed.</p>
55 </li>
56 </ol>
57 <p>Unless <i>chown</i> is invoked by a process with appropriate privileges, the set-user-ID and set-group-ID bits of a regular file
58 shall be cleared upon successful completion; the set-user-ID and set-group-ID bits of other file types may be cleared.</p>
59 </blockquote>
60 <h4 class="mansect"><a name="tag_20_18_04" id="tag_20_18_04"></a>OPTIONS</h4>
61 <blockquote>
62 <p>The <i>chown</i> utility shall conform to XBD <a href="../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax
63 Guidelines</i></a> .</p>
64 <p>The following options shall be supported by the implementation:</p>
65 <dl compact>
66 <dd></dd>
67 <dt><b>-h</b></dt>
68 <dd>For each file operand that names a file of type symbolic link, <i>chown</i> shall attempt to set the user ID of the symbolic
69 link. If a group ID was specified, for each file operand that names a file of type symbolic link, <i>chown</i> shall attempt to set
70 the group ID of the symbolic link.</dd>
71 <dt><b>-H</b></dt>
72 <dd>If the <b>-R</b> option is specified and a symbolic link referencing a file of type directory is specified on the command line,
73 <i>chown</i> shall change the user ID (and group ID, if specified) of the directory referenced by the symbolic link and all files
74 in the file hierarchy below it.</dd>
75 <dt><b>-L</b></dt>
76 <dd>If the <b>-R</b> option is specified and a symbolic link referencing a file of type directory is specified on the command line
77 or encountered during the traversal of a file hierarchy, <i>chown</i> shall change the user ID (and group ID, if specified) of the
78 directory referenced by the symbolic link and all files in the file hierarchy below it.</dd>
79 <dt><b>-P</b></dt>
80 <dd>If the <b>-R</b> option is specified and a symbolic link is specified on the command line or encountered during the traversal
81 of a file hierarchy, <i>chown</i> shall change the owner ID (and group ID, if specified) of the symbolic link. The <i>chown</i>
82 utility shall not follow the symbolic link to any other part of the file hierarchy.</dd>
83 <dt><b>-R</b></dt>
84 <dd>Recursively change file user and group IDs. For each <i>file</i> operand that names a directory, <i>chown</i> shall change the
85 user ID (and group ID, if specified) of the directory and all files in the file hierarchy below it. Unless a <b>-H</b>, <b>-L</b>,
86 or <b>-P</b> option is specified, it is unspecified which of these options will be used as the default.</dd>
87 </dl>
88 <p>Specifying more than one of the mutually-exclusive options <b>-H</b>, <b>-L</b>, and <b>-P</b> shall not be considered an error.
89 The last option specified shall determine the behavior of the utility.</p>
90 </blockquote>
91 <h4 class="mansect"><a name="tag_20_18_05" id="tag_20_18_05"></a>OPERANDS</h4>
92 <blockquote>
93 <p>The following operands shall be supported:</p>
94 <dl compact>
95 <dd></dd>
96 <dt><i>owner</i><b>[</b>:<i>group</i><b>]</b></dt>
97 <dd>A user ID and optional group ID to be assigned to <i>file</i>. The <i>owner</i> portion of this operand shall be a user name
98 from the user database or a numeric user ID. Either specifies a user ID which shall be given to each file named by one of the
99 <i>file</i> operands. If a numeric <i>owner</i> operand exists in the user database as a user name, the user ID number associated
100 with that user name shall be used as the user ID. Similarly, if the <i>group</i> portion of this operand is present, it shall be a
101 group name from the group database or a numeric group ID. Either specifies a group ID which shall be given to each file. If a
102 numeric group operand exists in the group database as a group name, the group ID number associated with that group name shall be
103 used as the group ID.</dd>
104 <dt><i>file</i></dt>
105 <dd>A pathname of a file whose user ID is to be modified.</dd>
106 </dl>
107 </blockquote>
108 <h4 class="mansect"><a name="tag_20_18_06" id="tag_20_18_06"></a>STDIN</h4>
109 <blockquote>
110 <p>Not used.</p>
111 </blockquote>
112 <h4 class="mansect"><a name="tag_20_18_07" id="tag_20_18_07"></a>INPUT FILES</h4>
113 <blockquote>
114 <p>None.</p>
115 </blockquote>
116 <h4 class="mansect"><a name="tag_20_18_08" id="tag_20_18_08"></a>ENVIRONMENT VARIABLES</h4>
117 <blockquote>
118 <p>The following environment variables shall affect the execution of <i>chown</i>:</p>
119 <dl compact>
120 <dd></dd>
121 <dt><i>LANG</i></dt>
122 <dd>Provide a default value for the internationalization variables that are unset or null. (See XBD <a href=
123 "../basedefs/V1_chap08.html#tag_08_02"><i>8.2 Internationalization Variables</i></a> for the precedence of internationalization
124 variables used to determine the values of locale categories.)</dd>
125 <dt><i>LC_ALL</i></dt>
126 <dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
127 <dt><i>LC_CTYPE</i></dt>
128 <dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
129 opposed to multi-byte characters in arguments).</dd>
130 <dt><i>LC_MESSAGES</i></dt>
131 <dd><br>
132 Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.</dd>
133 <dt><i>NLSPATH</i></dt>
134 <dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
135 Determine the location of messages objects and message catalogs. <img src="../images/opt-end.gif" alt="[Option End]" border=
136 "0"></dd>
137 </dl>
138 </blockquote>
139 <h4 class="mansect"><a name="tag_20_18_09" id="tag_20_18_09"></a>ASYNCHRONOUS EVENTS</h4>
140 <blockquote>
141 <p>Default.</p>
142 </blockquote>
143 <h4 class="mansect"><a name="tag_20_18_10" id="tag_20_18_10"></a>STDOUT</h4>
144 <blockquote>
145 <p>Not used.</p>
146 </blockquote>
147 <h4 class="mansect"><a name="tag_20_18_11" id="tag_20_18_11"></a>STDERR</h4>
148 <blockquote>
149 <p>The standard error shall be used only for diagnostic messages.</p>
150 </blockquote>
151 <h4 class="mansect"><a name="tag_20_18_12" id="tag_20_18_12"></a>OUTPUT FILES</h4>
152 <blockquote>
153 <p>None.</p>
154 </blockquote>
155 <h4 class="mansect"><a name="tag_20_18_13" id="tag_20_18_13"></a>EXTENDED DESCRIPTION</h4>
156 <blockquote>
157 <p>None.</p>
158 </blockquote>
159 <h4 class="mansect"><a name="tag_20_18_14" id="tag_20_18_14"></a>EXIT STATUS</h4>
160 <blockquote>
161 <p>The following exit values shall be returned:</p>
162 <dl compact>
163 <dd></dd>
164 <dt> 0</dt>
165 <dd>The utility executed successfully and all requested changes were made.</dd>
166 <dt>>0</dt>
167 <dd>An error occurred.</dd>
168 </dl>
169 </blockquote>
170 <h4 class="mansect"><a name="tag_20_18_15" id="tag_20_18_15"></a>CONSEQUENCES OF ERRORS</h4>
171 <blockquote>
172 <p>Default.</p>
173 </blockquote>
174 <hr>
175 <div class="box"><em>The following sections are informative.</em></div>
176 <h4 class="mansect"><a name="tag_20_18_16" id="tag_20_18_16"></a>APPLICATION USAGE</h4>
177 <blockquote>
178 <p>Only the owner of a file or the user with appropriate privileges may change the owner or group of a file.</p>
179 <p>Some implementations restrict the use of <i>chown</i> to a user with appropriate privileges.</p>
180 </blockquote>
181 <h4 class="mansect"><a name="tag_20_18_17" id="tag_20_18_17"></a>EXAMPLES</h4>
182 <blockquote>
183 <p>None.</p>
184 </blockquote>
185 <h4 class="mansect"><a name="tag_20_18_18" id="tag_20_18_18"></a>RATIONALE</h4>
186 <blockquote>
187 <p>The System V and BSD versions use different exit status codes. Some implementations used the exit status as a count of the
188 number of errors that occurred; this practice is unworkable since it can overflow the range of valid exit status values. These are
189 masked by specifying only 0 and >0 as exit values.</p>
190 <p>The functionality of <i>chown</i> is described substantially through references to functions in the System Interfaces volume of
191 POSIX.1-2024. In this way, there is no duplication of effort required for describing the interactions of permissions, multiple
192 groups, and so on.</p>
193 <p>The 4.3 BSD method of specifying both owner and group was included in this volume of POSIX.1-2024 because:</p>
194 <ul>
195 <li>
196 <p>There are cases where the desired end condition could not be achieved using the <a href=
197 "../utilities/chgrp.html"><i>chgrp</i></a> and <i>chown</i> (that only changed the user ID) utilities. (If the current owner is not
198 a member of the desired group and the desired owner is not a member of the current group, the <a href=
199 "../functions/chown.html"><i>chown</i>()</a> function could fail unless both owner and group are changed at the same time.)</p>
200 </li>
201 <li>
202 <p>Even if they could be changed independently, in cases where both are being changed, there is a 100% performance penalty caused
203 by being forced to invoke both utilities.</p>
204 </li>
205 </ul>
206 <p>The BSD syntax <i>user</i>[.<i>group</i>] was changed to <i>user</i>[:<i>group</i>] in this volume of POSIX.1-2024 because the
207 <period> is a valid character in login names (as specified by the Base Definitions volume of POSIX.1-2024, login names
208 consist of characters in the portable filename character set). The <colon> character was chosen as the replacement for the
209 <period> character because it would never be allowed as a character in a user name or group name on historical
210 implementations.</p>
211 <p>The <b>-R</b> option is considered by some observers as an undesirable departure from the historical UNIX system tools approach;
212 since a tool, <a href="../utilities/find.html"><i>find</i></a>, already exists to recurse over directories, there seemed to be no
213 good reason to require other tools to have to duplicate that functionality. However, the <b>-R</b> option was deemed an important
214 user convenience, is far more efficient than forking a separate process for each element of the directory hierarchy, and is in
215 widespread historical use.</p>
216 </blockquote>
217 <h4 class="mansect"><a name="tag_20_18_19" id="tag_20_18_19"></a>FUTURE DIRECTIONS</h4>
218 <blockquote>
219 <p>None.</p>
220 </blockquote>
221 <h4 class="mansect"><a name="tag_20_18_20" id="tag_20_18_20"></a>SEE ALSO</h4>
222 <blockquote>
223 <p><a href="../utilities/chgrp.html#"><i>chgrp</i></a> , <a href="../utilities/chmod.html#tag_20_17"><i>chmod</i></a></p>
224 <p>XBD <a href="../basedefs/V1_chap08.html#tag_08"><i>8. Environment Variables</i></a> , <a href=
225 "../basedefs/V1_chap12.html#tag_12_02"><i>12.2 Utility Syntax Guidelines</i></a></p>
226 <p>XSH <a href="../functions/chown.html#tag_17_73"><i>chown</i></a></p>
227 </blockquote>
228 <h4 class="mansect"><a name="tag_20_18_21" id="tag_20_18_21"></a>CHANGE HISTORY</h4>
229 <blockquote>
230 <p>First released in Issue 2.</p>
231 </blockquote>
232 <h4 class="mansect"><a name="tag_20_18_22" id="tag_20_18_22"></a>Issue 6</h4>
233 <blockquote>
234 <p>New options <b>-h</b>, <b>-H</b>, <b>-L</b>, and <b>-P</b> are added to align with the IEEE P1003.2b draft standard. These
235 options affect the processing of symbolic links.</p>
236 <p>The normative text is reworded to avoid use of the term "must" for application requirements.</p>
237 <p>IEEE PASC Interpretation 1003.2 #172 is applied, changing the CONSEQUENCES OF ERRORS section to "Default.".</p>
238 <p>The "otherwise, ..." text in item 3. of the DESCRIPTION is changed to "otherwise, the group ownership shall not be
239 changed".</p>
240 <p>IEEE Std 1003.1-2001/Cor 1-2002, item XCU/TC1/D6/17 is applied, changing the SYNOPSIS to make it clear that
241 <b>-h</b> and <b>-R</b> are optional.</p>
242 </blockquote>
243 <h4 class="mansect"><a name="tag_20_18_23" id="tag_20_18_23"></a>Issue 7</h4>
244 <blockquote>
245 <p>SD5-XCU-ERN-9 is applied, removing the <b>-R</b> from the first line of the SYNOPSIS.</p>
246 <p>SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.</p>
247 <p>The description of the <b>-h</b> and <b>-P</b> options is revised.</p>
248 </blockquote>
249 <h4 class="mansect"><a name="tag_20_18_24" id="tag_20_18_24"></a>Issue 8</h4>
250 <blockquote>
251 <p>Austin Group Defect 1122 is applied, changing the description of <i>NLSPATH .</i></p>
252 </blockquote>
253 <div class="box"><em>End of informative text.</em></div>
254 <hr>
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