1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- Copyright (C) 1988-2021 Free Software Foundation, Inc. 4 5Permission is granted to copy, distribute and/or modify this document 6under the terms of the GNU Free Documentation License, Version 1.3 or 7any later version published by the Free Software Foundation; with the 8Invariant Sections being "Free Software" and "Free Software Needs 9Free Documentation", with the Front-Cover Texts being "A GNU Manual," 10and with the Back-Cover Texts as in (a) below. 11 12(a) The FSF's Back-Cover Text is: "You are free to copy and modify 13this GNU Manual. 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For 75example, <code>print -pretty</code>. Similarly to command names, you can 76abbreviate a <small>GDB</small> option to the first few letters of the 77option name, if that abbreviation is unambiguous, and you can also use 78the <tt class="key">TAB</tt> key to get <small>GDB</small> to fill out the rest of a word 79in an option (or to show you the alternatives available, if there is 80more than one possibility). 81</p> 82<a name="index-command-options_002c-raw-input"></a> 83<p>Some commands take raw input as argument. For example, the print 84command processes arbitrary expressions in any of the languages 85supported by <small>GDB</small>. With such commands, because raw input may 86start with a leading dash that would be confused with an option or any 87of its abbreviations, e.g. <code>print -p</code> (short for <code>print 88-pretty</code> or printing negative <code>p</code>?), if you specify any command 89option, then you must use a double-dash (<code>--</code>) delimiter to 90indicate the end of options. 91</p> 92<a name="index-command-options_002c-boolean"></a> 93 94<p>Some options are described as accepting an argument which can be 95either <code>on</code> or <code>off</code>. These are known as <em>boolean 96options</em>. Similarly to boolean settings commands—<code>on</code> and 97<code>off</code> are the typical values, but any of <code>1</code>, <code>yes</code> and 98<code>enable</code> can also be used as “true” value, and any of <code>0</code>, 99<code>no</code> and <code>disable</code> can also be used as “false” value. You 100can also omit a “true” value, as it is implied by default. 101</p> 102<p>For example, these are equivalent: 103</p> 104<div class="smallexample"> 105<pre class="smallexample">(gdb) print -object on -pretty off -element unlimited -- *myptr 106(gdb) p -o -p 0 -e u -- *myptr 107</pre></div> 108 109<p>You can discover the set of options some command accepts by completing 110on <code>-</code> after the command name. For example: 111</p> 112<div class="smallexample"> 113<pre class="smallexample">(gdb) print -<span class="key">TAB</span><span class="key">TAB</span> 114-address -max-depth -raw-values -union 115-array -null-stop -repeats -vtbl 116-array-indexes -object -static-members 117-elements -pretty -symbol 118</pre></div> 119 120<p>Completion will in some cases guide you with a suggestion of what kind 121of argument an option expects. For example: 122</p> 123<div class="smallexample"> 124<pre class="smallexample">(gdb) print -elements <span class="key">TAB</span><span class="key">TAB</span> 125NUMBER unlimited 126</pre></div> 127 128<p>Here, the option expects a number (e.g., <code>100</code>), not literal 129<code>NUMBER</code>. Such metasyntactical arguments are always presented in 130uppercase. 131</p> 132<p>(For more on using the <code>print</code> command, see <a href="Data.html#Data">Examining 133Data</a>.) 134</p> 135<hr> 136<div class="header"> 137<p> 138Next: <a href="Command-aliases-default-args.html#Command-aliases-default-args" accesskey="n" rel="next">Command aliases default args</a>, Previous: <a href="Completion.html#Completion" accesskey="p" rel="previous">Completion</a>, Up: <a href="Commands.html#Commands" accesskey="u" rel="up">Commands</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p> 139</div> 140 141 142 143</body> 144</html> 145