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<title>Debugging with GDB: Frame Info</title>
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<a name="Frame-Info"></a>
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<div class="header">
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<p>
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Next: <a href="Frame-Apply.html#Frame-Apply" accesskey="n" rel="next">Frame Apply</a>, Previous: <a href="Selection.html#Selection" accesskey="p" rel="previous">Selection</a>, Up: <a href="Stack.html#Stack" accesskey="u" rel="up">Stack</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="Information-about-a-Frame"></a>
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<h3 class="section">8.4 Information about a Frame</h3>
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<p>There are several other commands to print information about the selected
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stack frame.
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</p>
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<dl compact="compact">
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<dt><code>frame</code></dt>
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<dt><code>f</code></dt>
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<dd><p>When used without any argument, this command does not change which
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frame is selected, but prints a brief description of the currently
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selected stack frame. It can be abbreviated <code>f</code>. With an
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argument, this command is used to select a stack frame.
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See <a href="Selection.html#Selection">Selecting a Frame</a>.
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</p>
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<a name="index-info-frame"></a>
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<a name="index-info-f-_0028info-frame_0029"></a>
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</dd>
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<dt><code>info frame</code></dt>
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<dt><code>info f</code></dt>
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<dd><p>This command prints a verbose description of the selected stack frame,
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including:
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</p>
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<ul>
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<li> the address of the frame
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</li><li> the address of the next frame down (called by this frame)
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</li><li> the address of the next frame up (caller of this frame)
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</li><li> the language in which the source code corresponding to this frame is written
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</li><li> the address of the frame’s arguments
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</li><li> the address of the frame’s local variables
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</li><li> the program counter saved in it (the address of execution in the caller frame)
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</li><li> which registers were saved in the frame
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</li></ul>
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<p>The verbose description is useful when
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something has gone wrong that has made the stack format fail to fit
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the usual conventions.
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</p>
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</dd>
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<dt><code>info frame <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
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<dt><code>info f <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
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<dd><p>Print a verbose description of the frame selected by
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<var>frame-selection-spec</var>. The <var>frame-selection-spec</var> is the
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same as for the <code>frame</code> command (see <a href="Selection.html#Selection">Selecting
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a Frame</a>). The selected frame remains unchanged by this command.
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</p>
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<a name="index-info-args"></a>
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</dd>
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<dt><code>info args [-q]</code></dt>
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<dd><p>Print the arguments of the selected frame, each on a separate line.
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</p>
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<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
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printing header information and messages explaining why no argument
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have been printed.
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</p>
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</dd>
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<dt><code>info args [-q] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
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<dd><p>Like <kbd>info args</kbd>, but only print the arguments selected
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with the provided regexp(s).
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</p>
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<p>If <var>regexp</var> is provided, print only the arguments whose names
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match the regular expression <var>regexp</var>.
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</p>
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<p>If <var>type_regexp</var> is provided, print only the arguments whose
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types, as printed by the <code>whatis</code> command, match
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the regular expression <var>type_regexp</var>.
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If <var>type_regexp</var> contains space(s), it should be enclosed in
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quote characters. If needed, use backslash to escape the meaning
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of special characters or quotes.
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</p>
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<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, an argument
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is printed only if its name matches <var>regexp</var> and its type matches
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<var>type_regexp</var>.
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</p>
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</dd>
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<dt><code>info locals [-q]</code></dt>
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<dd><a name="index-info-locals"></a>
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<p>Print the local variables of the selected frame, each on a separate
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line. These are all variables (declared either static or automatic)
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accessible at the point of execution of the selected frame.
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</p>
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<p>The optional flag ‘<samp>-q</samp>’, which stands for ‘<samp>quiet</samp>’, disables
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printing header information and messages explaining why no local variables
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have been printed.
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</p>
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</dd>
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<dt><code>info locals [-q] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
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<dd><p>Like <kbd>info locals</kbd>, but only print the local variables selected
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with the provided regexp(s).
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</p>
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<p>If <var>regexp</var> is provided, print only the local variables whose names
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match the regular expression <var>regexp</var>.
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</p>
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<p>If <var>type_regexp</var> is provided, print only the local variables whose
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types, as printed by the <code>whatis</code> command, match
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the regular expression <var>type_regexp</var>.
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If <var>type_regexp</var> contains space(s), it should be enclosed in
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quote characters. If needed, use backslash to escape the meaning
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of special characters or quotes.
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</p>
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<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, a local variable
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is printed only if its name matches <var>regexp</var> and its type matches
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<var>type_regexp</var>.
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</p>
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<p>The command <kbd>info locals -q -t <var>type_regexp</var></kbd> can usefully be
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combined with the commands <kbd>frame apply</kbd> and <kbd>thread apply</kbd>.
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For example, your program might use Resource Acquisition Is
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Initialization types (RAII) such as <code>lock_something_t</code>: each
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local variable of type <code>lock_something_t</code> automatically places a
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lock that is destroyed when the variable goes out of scope. You can
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then list all acquired locks in your program by doing
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</p><div class="smallexample">
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<pre class="smallexample">thread apply all -s frame apply all -s info locals -q -t lock_something_t
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</pre></div>
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<p>or the equivalent shorter form
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</p><div class="smallexample">
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<pre class="smallexample">tfaas i lo -q -t lock_something_t
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</pre></div>
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</dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Frame-Apply.html#Frame-Apply" accesskey="n" rel="next">Frame Apply</a>, Previous: <a href="Selection.html#Selection" accesskey="p" rel="previous">Selection</a>, Up: <a href="Stack.html#Stack" accesskey="u" rel="up">Stack</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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