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<title>Debugging with GDB: Command Settings</title>
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<a name="Command-Settings"></a>
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Next: <a href="Completion.html#Completion" accesskey="n" rel="next">Completion</a>, Previous: <a href="Command-Syntax.html#Command-Syntax" accesskey="p" rel="previous">Command Syntax</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>
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<a name="Command-Settings-1"></a>
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<h3 class="section">3.2 Command Settings</h3>
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<a name="index-default-behavior-of-commands_002c-changing"></a>
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<a name="index-default-settings_002c-changing"></a>
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<p>Many commands change their behavior according to command-specific
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variables or settings. These settings can be changed with the
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<code>set</code> subcommands. For example, the <code>print</code> command
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(see <a href="Data.html#Data">Examining Data</a>) prints arrays differently depending on
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settings changeable with the commands <code>set print elements
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NUMBER-OF-ELEMENTS</code> and <code>set print array-indexes</code>, among others.
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</p>
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<p>You can change these settings to your preference in the gdbinit files
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loaded at <small>GDB</small> startup. See <a href="Startup.html#Startup">Startup</a>.
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</p>
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<p>The settings can also be changed interactively during the debugging
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session. For example, to change the limit of array elements to print,
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you can do the following:
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</p><div class="smallexample">
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<pre class="smallexample">(GDB) set print elements 10
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(GDB) print some_array
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$1 = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90...}
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</pre></div>
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<p>The above <code>set print elements 10</code> command changes the number of
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elements to print from the default of 200 to 10. If you only intend
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this limit of 10 to be used for printing <code>some_array</code>, then you
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must restore the limit back to 200, with <code>set print elements
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200</code>.
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</p>
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<p>Some commands allow overriding settings with command options. For
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example, the <code>print</code> command supports a number of options that
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allow overriding relevant global print settings as set by <code>set
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print</code> subcommands. See <a href="Data.html#print-options">print options</a>. The example above could be
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rewritten as:
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</p><div class="smallexample">
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<pre class="smallexample">(GDB) print -elements 10 -- some_array
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$1 = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90...}
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</pre></div>
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<p>Alternatively, you can use the <code>with</code> command to change a setting
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temporarily, for the duration of a command invocation.
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</p>
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<dl compact="compact">
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<dd><a name="index-with-command"></a>
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<a name="index-w-_0028with_0029"></a>
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<a name="index-settings"></a>
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<a name="index-temporarily-change-settings"></a>
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</dd>
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<dt><code>with <var>setting</var> [<var>value</var>] [-- <var>command</var>]</code></dt>
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<dt><code>w <var>setting</var> [<var>value</var>] [-- <var>command</var>]</code></dt>
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<dd><p>Temporarily set <var>setting</var> to <var>value</var> for the duration of
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<var>command</var>.
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</p>
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<p><var>setting</var> is any setting you can change with the <code>set</code>
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subcommands. <var>value</var> is the value to assign to <code>setting</code>
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while running <code>command</code>.
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</p>
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<p>If no <var>command</var> is provided, the last command executed is
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repeated.
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</p>
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<p>If a <var>command</var> is provided, it must be preceded by a double dash
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(<code>--</code>) separator. This is required because some settings accept
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free-form arguments, such as expressions or filenames.
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</p>
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<p>For example, the command
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</p><div class="smallexample">
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<pre class="smallexample">(GDB) with print array on -- print some_array
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</pre></div>
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<p>is equivalent to the following 3 commands:
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</p><div class="smallexample">
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<pre class="smallexample">(GDB) set print array on
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(GDB) print some_array
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(GDB) set print array off
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</pre></div>
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<p>The <code>with</code> command is particularly useful when you want to
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override a setting while running user-defined commands, or commands
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defined in Python or Guile. See <a href="Extending-GDB.html#Extending-GDB">Extending GDB</a>.
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</p>
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<div class="smallexample">
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<pre class="smallexample">(GDB) with print pretty on -- my_complex_command
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</pre></div>
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<p>To change several settings for the same command, you can nest
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<code>with</code> commands. For example, <code>with language ada -- with
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print elements 10</code> temporarily changes the language to Ada and sets a
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limit of 10 elements to print for arrays and strings.
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</p>
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</dd>
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<p>
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Next: <a href="Completion.html#Completion" accesskey="n" rel="next">Completion</a>, Previous: <a href="Command-Syntax.html#Command-Syntax" accesskey="p" rel="previous">Command Syntax</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>
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