155 lines
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155 lines
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<title>Frame Apply - Debugging with GDB</title>
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<link rel="up" href="Stack.html#Stack" title="Stack">
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<link rel="prev" href="Frame-Info.html#Frame-Info" title="Frame Info">
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<link rel="next" href="Frame-Filter-Management.html#Frame-Filter-Management" title="Frame Filter Management">
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<a name="Frame-Apply"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Frame-Filter-Management.html#Frame-Filter-Management">Frame Filter Management</a>,
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Previous: <a rel="previous" accesskey="p" href="Frame-Info.html#Frame-Info">Frame Info</a>,
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Up: <a rel="up" accesskey="u" href="Stack.html#Stack">Stack</a>
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<hr>
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</div>
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<h3 class="section">8.5 Applying a Command to Several Frames.</h3>
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<p><a name="index-frame-apply-545"></a><a name="index-apply-command-to-several-frames-546"></a>
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<dl>
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<dt><code>frame apply [all | </code><var>count</var><code> | </code><var>-count</var><code> | level </code><var>level</var><code>...] [</code><var>flag</var><code>]... </code><var>command</var><dd>The <code>frame apply</code> command allows you to apply the named
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<var>command</var> to one or more frames.
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<dl>
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<dt><code>all</code><dd>Specify <code>all</code> to apply <var>command</var> to all frames.
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<br><dt><var>count</var><dd>Use <var>count</var> to apply <var>command</var> to the innermost <var>count</var>
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frames, where <var>count</var> is a positive number.
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<br><dt><var>-count</var><dd>Use <var>-count</var> to apply <var>command</var> to the outermost <var>count</var>
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frames, where <var>count</var> is a positive number.
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<br><dt><code>level</code><dd>Use <code>level</code> to apply <var>command</var> to the set of frames identified
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by the <var>level</var> list. <var>level</var> is a frame level or a range of frame
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levels as <var>level1</var>-<var>level2</var>. The frame level is the number shown
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in the first field of the ‘<samp><span class="samp">backtrace</span></samp>’ command output.
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E.g., ‘<samp><span class="samp">2-4 6-8 3</span></samp>’ indicates to apply <var>command</var> for the frames
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at levels 2, 3, 4, 6, 7, 8, and then again on frame at level 3.
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</dl>
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</dl>
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<p>Note that the frames on which <code>frame apply</code> applies a command are
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also influenced by the <code>set backtrace</code> settings such as <code>set
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backtrace past-main</code> and <code>set backtrace limit N</code>. See
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See <a href="Backtrace.html#Backtrace">Backtraces</a>.
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<p>The <var>flag</var> arguments control what output to produce and how to handle
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errors raised when applying <var>command</var> to a frame. <var>flag</var>
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must start with a <code>-</code> directly followed by one letter in
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<code>qcs</code>. If several flags are provided, they must be given
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individually, such as <code>-c -q</code>.
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<p>By default, <span class="sc">gdb</span> displays some frame information before the
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output produced by <var>command</var>, and an error raised during the
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execution of a <var>command</var> will abort <code>frame apply</code>. The
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following flags can be used to fine-tune this behavior:
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<dl>
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<dt><code>-c</code><dd>The flag <code>-c</code>, which stands for ‘<samp><span class="samp">continue</span></samp>’, causes any
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errors in <var>command</var> to be displayed, and the execution of
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<code>frame apply</code> then continues.
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<br><dt><code>-s</code><dd>The flag <code>-s</code>, which stands for ‘<samp><span class="samp">silent</span></samp>’, causes any errors
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or empty output produced by a <var>command</var> to be silently ignored.
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That is, the execution continues, but the frame information and errors
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are not printed.
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<br><dt><code>-q</code><dd>The flag <code>-q</code> (‘<samp><span class="samp">quiet</span></samp>’) disables printing the frame
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information.
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</dl>
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<p>The following example shows how the flags <code>-c</code> and <code>-s</code> are
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working when applying the command <code>p j</code> to all frames, where
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variable <code>j</code> can only be successfully printed in the outermost
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<code>#1 main</code> frame.
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<pre class="smallexample"> (gdb) frame apply all p j
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#0 some_function (i=5) at fun.c:4
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No symbol "j" in current context.
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(gdb) frame apply all -c p j
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#0 some_function (i=5) at fun.c:4
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No symbol "j" in current context.
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#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
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$1 = 5
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(gdb) frame apply all -s p j
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#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
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$2 = 5
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(gdb)
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</pre>
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<p>By default, ‘<samp><span class="samp">frame apply</span></samp>’, prints the frame location
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information before the command output:
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<pre class="smallexample"> (gdb) frame apply all p $sp
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#0 some_function (i=5) at fun.c:4
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$4 = (void *) 0xffffd1e0
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#1 0x565555fb in main (argc=1, argv=0xffffd2c4) at fun.c:11
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$5 = (void *) 0xffffd1f0
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(gdb)
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</pre>
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<p>If flag <code>-q</code> is given, no frame information is printed:
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<pre class="smallexample"> (gdb) frame apply all -q p $sp
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$12 = (void *) 0xffffd1e0
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$13 = (void *) 0xffffd1f0
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(gdb)
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</pre>
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<a name="index-faas-547"></a>
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<a name="index-apply-a-command-to-all-frames-_0028ignoring-errors-and-empty-output_0029-548"></a>
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<dl><dt><code>faas </code><var>command</var><dd>Shortcut for <code>frame apply all -s </code><var>command</var>.
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Applies <var>command</var> on all frames, ignoring errors and empty output.
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<p>It can for example be used to print a local variable or a function
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argument without knowing the frame where this variable or argument
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is, using:
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<pre class="smallexample"> (gdb) faas p some_local_var_i_do_not_remember_where_it_is
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</pre>
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<p>Note that the command <code>tfaas </code><var>command</var> applies <var>command</var>
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on all frames of all threads. See See <a href="Threads.html#Threads">Threads</a>.
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</dl>
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</body></html>
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