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23 <center><font size="2">The Open Group Base Specifications Issue 8<br>
24 IEEE Std 1003.1-2024<br>
25 Copyright © 2001-2024 The IEEE and The Open Group</font></center>
26 <hr size="2" noshade>
27 <a name="top" id="top"></a> <a name="true" id="true"></a> <a name="tag_20_127" id="tag_20_127"></a><!-- true -->
28 <h4 class="mansect"><a name="tag_20_127_01" id="tag_20_127_01"></a>NAME</h4>
29 <blockquote>true — return true value</blockquote>
30 <h4 class="mansect"><a name="tag_20_127_02" id="tag_20_127_02"></a>SYNOPSIS</h4>
31 <blockquote class="synopsis">
32 <p><code><tt>true</tt></code></p>
33 </blockquote>
34 <h4 class="mansect"><a name="tag_20_127_03" id="tag_20_127_03"></a>DESCRIPTION</h4>
35 <blockquote>
36 <p>The <i>true</i> utility shall return with exit code zero.</p>
37 </blockquote>
38 <h4 class="mansect"><a name="tag_20_127_04" id="tag_20_127_04"></a>OPTIONS</h4>
39 <blockquote>
40 <p>None.</p>
41 </blockquote>
42 <h4 class="mansect"><a name="tag_20_127_05" id="tag_20_127_05"></a>OPERANDS</h4>
43 <blockquote>
44 <p>None.</p>
45 </blockquote>
46 <h4 class="mansect"><a name="tag_20_127_06" id="tag_20_127_06"></a>STDIN</h4>
47 <blockquote>
48 <p>Not used.</p>
49 </blockquote>
50 <h4 class="mansect"><a name="tag_20_127_07" id="tag_20_127_07"></a>INPUT FILES</h4>
51 <blockquote>
52 <p>None.</p>
53 </blockquote>
54 <h4 class="mansect"><a name="tag_20_127_08" id="tag_20_127_08"></a>ENVIRONMENT VARIABLES</h4>
55 <blockquote>
56 <p>None.</p>
57 </blockquote>
58 <h4 class="mansect"><a name="tag_20_127_09" id="tag_20_127_09"></a>ASYNCHRONOUS EVENTS</h4>
59 <blockquote>
60 <p>Default.</p>
61 </blockquote>
62 <h4 class="mansect"><a name="tag_20_127_10" id="tag_20_127_10"></a>STDOUT</h4>
63 <blockquote>
64 <p>Not used.</p>
65 </blockquote>
66 <h4 class="mansect"><a name="tag_20_127_11" id="tag_20_127_11"></a>STDERR</h4>
67 <blockquote>
68 <p>Not used.</p>
69 </blockquote>
70 <h4 class="mansect"><a name="tag_20_127_12" id="tag_20_127_12"></a>OUTPUT FILES</h4>
71 <blockquote>
72 <p>None.</p>
73 </blockquote>
74 <h4 class="mansect"><a name="tag_20_127_13" id="tag_20_127_13"></a>EXTENDED DESCRIPTION</h4>
75 <blockquote>
76 <p>None.</p>
77 </blockquote>
78 <h4 class="mansect"><a name="tag_20_127_14" id="tag_20_127_14"></a>EXIT STATUS</h4>
79 <blockquote>
80 <p>Zero.</p>
81 </blockquote>
82 <h4 class="mansect"><a name="tag_20_127_15" id="tag_20_127_15"></a>CONSEQUENCES OF ERRORS</h4>
83 <blockquote>
84 <p>None.</p>
85 </blockquote>
86 <hr>
87 <div class="box"><em>The following sections are informative.</em></div>
88 <h4 class="mansect"><a name="tag_20_127_16" id="tag_20_127_16"></a>APPLICATION USAGE</h4>
89 <blockquote>
90 <p>This utility is typically used in shell scripts, as shown in the EXAMPLES section.</p>
91 <p>Although the special built-in utility <b>:</b> (<a href="../utilities/colon.html"><i>colon</i></a>) is similar to <i>true</i>,
92 there are some notable differences, including:</p>
93 <ul>
94 <li>
95 <p>Whereas <a href="../utilities/colon.html"><i>colon</i></a> is required to accept, and do nothing with, any number of arguments,
96 <i>true</i> is only required to accept, and discard, a first argument of <tt>"--"</tt>. Passing any other argument(s) to
97 <i>true</i> may cause its behavior to differ from that described in this standard.</p>
98 </li>
99 <li>
100 <p>A non-interactive shell exits when a redirection error occurs with <a href="../utilities/colon.html"><i>colon</i></a> (unless
101 executed via <a href="../utilities/command.html"><i>command</i></a>), whereas with <i>true</i> it does not.</p>
102 </li>
103 <li>
104 <p>Variable assignments preceding the command name persist after executing <a href="../utilities/colon.html"><i>colon</i></a>
105 (unless executed via <a href="../utilities/command.html"><i>command</i></a>), but not after executing <i>true</i>.</p>
106 </li>
107 <li>
108 <p>In shell implementations where <i>true</i> is not provided as a built-in, using <a href=
109 "../utilities/colon.html"><i>colon</i></a> avoids the overheads associated with executing an external utility.</p>
110 </li>
111 </ul>
112 </blockquote>
113 <h4 class="mansect"><a name="tag_20_127_17" id="tag_20_127_17"></a>EXAMPLES</h4>
114 <blockquote>
115 <p>This command is executed forever:</p>
116 <pre>
117 <tt>while true
118 do
119 command
120 done
121 </tt></pre></blockquote>
122 <h4 class="mansect"><a name="tag_20_127_18" id="tag_20_127_18"></a>RATIONALE</h4>
123 <blockquote>
124 <p>None.</p>
125 </blockquote>
126 <h4 class="mansect"><a name="tag_20_127_19" id="tag_20_127_19"></a>FUTURE DIRECTIONS</h4>
127 <blockquote>
128 <p>None.</p>
129 </blockquote>
130 <h4 class="mansect"><a name="tag_20_127_20" id="tag_20_127_20"></a>SEE ALSO</h4>
131 <blockquote>
132 <p><a href="../utilities/V3_chap02.html#tag_19_09"><i>2.9 Shell Commands</i></a> , <a href=
133 "../utilities/V3_chap02.html#tag_19_17"><i>colon</i></a> , <a href="../utilities/command.html#"><i>command</i></a> , <a href=
134 "../utilities/false.html#"><i>false</i></a></p>
135 </blockquote>
136 <h4 class="mansect"><a name="tag_20_127_21" id="tag_20_127_21"></a>CHANGE HISTORY</h4>
137 <blockquote>
138 <p>First released in Issue 2.</p>
139 </blockquote>
140 <h4 class="mansect"><a name="tag_20_127_22" id="tag_20_127_22"></a>Issue 6</h4>
141 <blockquote>
142 <p>IEEE Std 1003.1-2001/Cor 1-2002, item XCU/TC1/D6/39 is applied, replacing the terms "None" and "Default" from
143 the STDERR and EXIT STATUS sections, respectively, with terms as defined in <a href="../utilities/V3_chap01.html#tag_18_04"><i>1.4
144 Utility Description Defaults</i></a> .</p>
145 </blockquote>
146 <h4 class="mansect"><a name="tag_20_127_23" id="tag_20_127_23"></a>Issue 8</h4>
147 <blockquote>
148 <p>Austin Group Defect 1640 is applied, clarifying the differences between <i>true</i> and <b>:</b> (<a href=
149 "../utilities/colon.html"><i>colon</i></a>).</p>
150 </blockquote>
151 <div class="box"><em>End of informative text.</em></div>
152 <hr>
153 <p> </p>
154 <a href="#top"><span class="topOfPage">return to top of page</span></a><br>
155 <hr size="2" noshade>
156 <center><font size="2">UNIX® is a registered Trademark of The Open Group.<br>
157 POSIX™ is a Trademark of The IEEE.<br>
158 Copyright © 2001-2024 The IEEE and The Open Group, All Rights Reserved<br>
159 [ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
160 "../functions/contents.html">XSH</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../xrat/contents.html">XRAT</a>
161 ]</font></center>
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