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<title>Debugging with GDB: Skipping Over Functions and Files</title>
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<a name="Skipping-Over-Functions-and-Files"></a>
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<div class="header">
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<p>
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Next: <a href="Signals.html#Signals" accesskey="n" rel="next">Signals</a>, Previous: <a href="Continuing-and-Stepping.html#Continuing-and-Stepping" accesskey="p" rel="previous">Continuing and Stepping</a>, Up: <a href="Stopping.html#Stopping" accesskey="u" rel="up">Stopping</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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<hr>
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<a name="Skipping-over-Functions-and-Files"></a>
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<h3 class="section">5.3 Skipping over Functions and Files</h3>
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<a name="index-skipping-over-functions-and-files"></a>
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<p>The program you are debugging may contain some functions which are
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uninteresting to debug. The <code>skip</code> command lets you tell <small>GDB</small> to
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skip a function, all functions in a file or a particular function in
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a particular file when stepping.
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</p>
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<p>For example, consider the following C function:
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</p>
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<div class="smallexample">
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<pre class="smallexample">101 int func()
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102 {
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103 foo(boring());
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104 bar(boring());
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105 }
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</pre></div>
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<p>Suppose you wish to step into the functions <code>foo</code> and <code>bar</code>, but you
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are not interested in stepping through <code>boring</code>. If you run <code>step</code>
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at line 103, you’ll enter <code>boring()</code>, but if you run <code>next</code>, you’ll
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step over both <code>foo</code> and <code>boring</code>!
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</p>
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<p>One solution is to <code>step</code> into <code>boring</code> and use the <code>finish</code>
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command to immediately exit it. But this can become tedious if <code>boring</code>
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is called from many places.
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</p>
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<p>A more flexible solution is to execute <kbd>skip boring</kbd>. This instructs
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<small>GDB</small> never to step into <code>boring</code>. Now when you execute
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<code>step</code> at line 103, you’ll step over <code>boring</code> and directly into
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<code>foo</code>.
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</p>
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<p>Functions may be skipped by providing either a function name, linespec
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(see <a href="Specify-Location.html#Specify-Location">Specify Location</a>), regular expression that matches the function’s
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name, file name or a <code>glob</code>-style pattern that matches the file name.
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</p>
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<p>On Posix systems the form of the regular expression is
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“Extended Regular Expressions”. See for example ‘<samp>man 7 regex</samp>’
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on <small>GNU</small>/Linux systems. On non-Posix systems the form of the regular
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expression is whatever is provided by the <code>regcomp</code> function of
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the underlying system.
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See for example ‘<samp>man 7 glob</samp>’ on <small>GNU</small>/Linux systems for a
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description of <code>glob</code>-style patterns.
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</p>
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<dl compact="compact">
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<dd><a name="index-skip"></a>
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</dd>
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<dt><code>skip <span class="roman">[</span><var>options</var><span class="roman">]</span></code></dt>
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<dd><p>The basic form of the <code>skip</code> command takes zero or more options
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that specify what to skip.
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The <var>options</var> argument is any useful combination of the following:
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</p>
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<dl compact="compact">
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<dt><code>-file <var>file</var></code></dt>
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<dt><code>-fi <var>file</var></code></dt>
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<dd><p>Functions in <var>file</var> will be skipped over when stepping.
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</p>
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</dd>
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<dt><code>-gfile <var>file-glob-pattern</var></code></dt>
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<dt><code>-gfi <var>file-glob-pattern</var></code></dt>
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<dd><a name="index-skipping-over-files-via-glob_002dstyle-patterns"></a>
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<p>Functions in files matching <var>file-glob-pattern</var> will be skipped
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over when stepping.
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</p>
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<div class="smallexample">
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<pre class="smallexample">(gdb) skip -gfi utils/*.c
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</pre></div>
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</dd>
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<dt><code>-function <var>linespec</var></code></dt>
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<dt><code>-fu <var>linespec</var></code></dt>
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<dd><p>Functions named by <var>linespec</var> or the function containing the line
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named by <var>linespec</var> will be skipped over when stepping.
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See <a href="Specify-Location.html#Specify-Location">Specify Location</a>.
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</p>
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</dd>
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<dt><code>-rfunction <var>regexp</var></code></dt>
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<dt><code>-rfu <var>regexp</var></code></dt>
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<dd><a name="index-skipping-over-functions-via-regular-expressions"></a>
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<p>Functions whose name matches <var>regexp</var> will be skipped over when stepping.
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</p>
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<p>This form is useful for complex function names.
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For example, there is generally no need to step into C<tt>++</tt> <code>std::string</code>
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constructors or destructors. Plus with C<tt>++</tt> templates it can be hard to
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write out the full name of the function, and often it doesn’t matter what
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the template arguments are. Specifying the function to be skipped as a
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regular expression makes this easier.
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</p>
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<div class="smallexample">
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<pre class="smallexample">(gdb) skip -rfu ^std::(allocator|basic_string)<.*>::~?\1 *\(
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</pre></div>
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<p>If you want to skip every templated C<tt>++</tt> constructor and destructor
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in the <code>std</code> namespace you can do:
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</p>
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<div class="smallexample">
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<pre class="smallexample">(gdb) skip -rfu ^std::([a-zA-z0-9_]+)<.*>::~?\1 *\(
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</pre></div>
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</dd>
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</dl>
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<p>If no options are specified, the function you’re currently debugging
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will be skipped.
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</p>
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<a name="index-skip-function"></a>
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</dd>
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<dt><code>skip function <span class="roman">[</span><var>linespec</var><span class="roman">]</span></code></dt>
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<dd><p>After running this command, the function named by <var>linespec</var> or the
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function containing the line named by <var>linespec</var> will be skipped over when
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stepping. See <a href="Specify-Location.html#Specify-Location">Specify Location</a>.
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</p>
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<p>If you do not specify <var>linespec</var>, the function you’re currently debugging
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will be skipped.
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</p>
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<p>(If you have a function called <code>file</code> that you want to skip, use
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<kbd>skip function file</kbd>.)
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</p>
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<a name="index-skip-file"></a>
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</dd>
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<dt><code>skip file <span class="roman">[</span><var>filename</var><span class="roman">]</span></code></dt>
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<dd><p>After running this command, any function whose source lives in <var>filename</var>
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will be skipped over when stepping.
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</p>
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<div class="smallexample">
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<pre class="smallexample">(gdb) skip file boring.c
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File boring.c will be skipped when stepping.
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</pre></div>
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<p>If you do not specify <var>filename</var>, functions whose source lives in the file
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you’re currently debugging will be skipped.
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</p></dd>
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</dl>
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<p>Skips can be listed, deleted, disabled, and enabled, much like breakpoints.
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These are the commands for managing your list of skips:
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</p>
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<dl compact="compact">
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<dd><a name="index-info-skip"></a>
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</dd>
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<dt><code>info skip <span class="roman">[</span><var>range</var><span class="roman">]</span></code></dt>
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<dd><p>Print details about the specified skip(s). If <var>range</var> is not specified,
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print a table with details about all functions and files marked for skipping.
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<code>info skip</code> prints the following information about each skip:
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</p>
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<dl compact="compact">
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<dt><em>Identifier</em></dt>
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<dd><p>A number identifying this skip.
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</p></dd>
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<dt><em>Enabled or Disabled</em></dt>
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<dd><p>Enabled skips are marked with ‘<samp>y</samp>’.
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Disabled skips are marked with ‘<samp>n</samp>’.
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</p></dd>
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<dt><em>Glob</em></dt>
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<dd><p>If the file name is a ‘<samp>glob</samp>’ pattern this is ‘<samp>y</samp>’.
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Otherwise it is ‘<samp>n</samp>’.
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</p></dd>
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<dt><em>File</em></dt>
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<dd><p>The name or ‘<samp>glob</samp>’ pattern of the file to be skipped.
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If no file is specified this is ‘<samp><none></samp>’.
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</p></dd>
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<dt><em>RE</em></dt>
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<dd><p>If the function name is a ‘<samp>regular expression</samp>’ this is ‘<samp>y</samp>’.
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Otherwise it is ‘<samp>n</samp>’.
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</p></dd>
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<dt><em>Function</em></dt>
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<dd><p>The name or regular expression of the function to skip.
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If no function is specified this is ‘<samp><none></samp>’.
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</p></dd>
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</dl>
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<a name="index-skip-delete"></a>
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</dd>
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<dt><code>skip delete <span class="roman">[</span><var>range</var><span class="roman">]</span></code></dt>
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<dd><p>Delete the specified skip(s). If <var>range</var> is not specified, delete all
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skips.
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</p>
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<a name="index-skip-enable"></a>
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</dd>
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<dt><code>skip enable <span class="roman">[</span><var>range</var><span class="roman">]</span></code></dt>
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<dd><p>Enable the specified skip(s). If <var>range</var> is not specified, enable all
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skips.
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</p>
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<a name="index-skip-disable"></a>
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</dd>
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<dt><code>skip disable <span class="roman">[</span><var>range</var><span class="roman">]</span></code></dt>
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<dd><p>Disable the specified skip(s). If <var>range</var> is not specified, disable all
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skips.
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</p>
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<a name="index-set-debug-skip"></a>
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</dd>
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<dt><code>set debug skip <span class="roman">[</span>on|off<span class="roman">]</span></code></dt>
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<dd><p>Set whether to print the debug output about skipping files and functions.
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</p>
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<a name="index-show-debug-skip"></a>
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</dd>
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<dt><code>show debug skip</code></dt>
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<dd><p>Show whether the debug output about skipping files and functions is printed.
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</p>
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</dd>
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</dl>
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<hr>
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Next: <a href="Signals.html#Signals" accesskey="n" rel="next">Signals</a>, Previous: <a href="Continuing-and-Stepping.html#Continuing-and-Stepping" accesskey="p" rel="previous">Continuing and Stepping</a>, Up: <a href="Stopping.html#Stopping" accesskey="u" rel="up">Stopping</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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