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<title>Debugging with GDB: Frame Info</title>

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<a name="Frame-Info"></a>
<div class="header">
<p>
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> &nbsp; [<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>
</div>
<hr>
<a name="Information-About-a-Frame"></a>
<h3 class="section">8.4 Information About a Frame</h3>

<p>There are several other commands to print information about the selected
stack frame.
</p>
<dl compact="compact">
<dt><code>frame</code></dt>
<dt><code>f</code></dt>
<dd><p>When used without any argument, this command does not change which
frame is selected, but prints a brief description of the currently
selected stack frame.  It can be abbreviated <code>f</code>.  With an
argument, this command is used to select a stack frame.
See <a href="Selection.html#Selection">Selecting a Frame</a>.
</p>
<a name="index-info-frame"></a>
<a name="index-info-f-_0028info-frame_0029"></a>
</dd>
<dt><code>info frame</code></dt>
<dt><code>info f</code></dt>
<dd><p>This command prints a verbose description of the selected stack frame,
including:
</p>
<ul>
<li> the address of the frame
</li><li> the address of the next frame down (called by this frame)
</li><li> the address of the next frame up (caller of this frame)
</li><li> the language in which the source code corresponding to this frame is written
</li><li> the address of the frame&rsquo;s arguments
</li><li> the address of the frame&rsquo;s local variables
</li><li> the program counter saved in it (the address of execution in the caller frame)
</li><li> which registers were saved in the frame
</li></ul>

<p>The verbose description is useful when
something has gone wrong that has made the stack format fail to fit
the usual conventions.
</p>
</dd>
<dt><code>info frame <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
<dt><code>info f <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
<dd><p>Print a verbose description of the frame selected by
<var>frame-selection-spec</var>.  The <var>frame-selection-spec</var> is the
same as for the <code>frame</code> command (see <a href="Selection.html#Selection">Selecting
a Frame</a>).  The selected frame remains unchanged by this command.
</p>
<a name="index-info-args"></a>
</dd>
<dt><code>info args [-q]</code></dt>
<dd><p>Print the arguments of the selected frame, each on a separate line.
</p>
<p>The optional flag &lsquo;<samp>-q</samp>&rsquo;, which stands for &lsquo;<samp>quiet</samp>&rsquo;, disables
printing header information and messages explaining why no argument
have been printed.
</p>
</dd>
<dt><code>info args [-q] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
<dd><p>Like <kbd>info args</kbd>, but only print the arguments selected
with the provided regexp(s).
</p>
<p>If <var>regexp</var> is provided, print only the arguments whose names
match the regular expression <var>regexp</var>.
</p>
<p>If <var>type_regexp</var> is provided, print only the arguments whose
types, as printed by the <code>whatis</code> command, match
the regular expression <var>type_regexp</var>.
If <var>type_regexp</var> contains space(s), it should be enclosed in
quote characters.  If needed, use backslash to escape the meaning
of special characters or quotes.
</p>
<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, an argument
is printed only if its name matches <var>regexp</var> and its type matches
<var>type_regexp</var>.
</p>
</dd>
<dt><code>info locals [-q]</code></dt>
<dd><a name="index-info-locals"></a>
<p>Print the local variables of the selected frame, each on a separate
line.  These are all variables (declared either static or automatic)
accessible at the point of execution of the selected frame.
</p>
<p>The optional flag &lsquo;<samp>-q</samp>&rsquo;, which stands for &lsquo;<samp>quiet</samp>&rsquo;, disables
printing header information and messages explaining why no local variables
have been printed.
</p>
</dd>
<dt><code>info locals [-q] [-t <var>type_regexp</var>] [<var>regexp</var>]</code></dt>
<dd><p>Like <kbd>info locals</kbd>, but only print the local variables selected
with the provided regexp(s).
</p>
<p>If <var>regexp</var> is provided, print only the local variables whose names
match the regular expression <var>regexp</var>.
</p>
<p>If <var>type_regexp</var> is provided, print only the local variables whose
types, as printed by the <code>whatis</code> command, match
the regular expression <var>type_regexp</var>.
If <var>type_regexp</var> contains space(s), it should be enclosed in
quote characters.  If needed, use backslash to escape the meaning
of special characters or quotes.
</p>
<p>If both <var>regexp</var> and <var>type_regexp</var> are provided, a local variable
is printed only if its name matches <var>regexp</var> and its type matches
<var>type_regexp</var>.
</p>
<p>The command <kbd>info locals -q -t <var>type_regexp</var></kbd> can usefully be
combined with the commands <kbd>frame apply</kbd> and <kbd>thread apply</kbd>.
For example, your program might use Resource Acquisition Is
Initialization types (RAII) such as <code>lock_something_t</code>: each
local variable of type <code>lock_something_t</code> automatically places a
lock that is destroyed when the variable goes out of scope.  You can
then list all acquired locks in your program by doing
</p><div class="smallexample">
<pre class="smallexample">thread apply all -s frame apply all -s info locals -q -t lock_something_t
</pre></div>
<p>or the equivalent shorter form
</p><div class="smallexample">
<pre class="smallexample">tfaas i lo -q -t lock_something_t
</pre></div>

</dd>
</dl>

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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> &nbsp; [<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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