You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
229 lines
9.6 KiB
HTML
229 lines
9.6 KiB
HTML
4 years ago
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
|
|
<html>
|
||
|
|
<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
Permission is granted to copy, distribute and/or modify this document
|
||
|
|
under the terms of the GNU Free Documentation License, Version 1.3 or
|
||
|
|
any later version published by the Free Software Foundation; with the
|
||
|
|
Invariant Sections being "Free Software" and "Free Software Needs
|
||
|
|
Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
|
||
|
|
and with the Back-Cover Texts as in (a) below.
|
||
|
|
|
||
|
|
(a) The FSF's Back-Cover Text is: "You are free to copy and modify
|
||
|
|
this GNU Manual. Buying copies from GNU Press supports the FSF in
|
||
|
|
developing GNU and promoting software freedom." -->
|
||
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
||
|
|
<head>
|
||
|
|
<title>Selection (Debugging with GDB)</title>
|
||
|
|
|
||
|
|
<meta name="description" content="Selection (Debugging with GDB)">
|
||
|
|
<meta name="keywords" content="Selection (Debugging with GDB)">
|
||
|
|
<meta name="resource-type" content="document">
|
||
|
|
<meta name="distribution" content="global">
|
||
|
|
<meta name="Generator" content="makeinfo">
|
||
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
||
|
|
<link href="index.html#Top" rel="start" title="Top">
|
||
|
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
||
|
|
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
|
||
|
|
<link href="Stack.html#Stack" rel="up" title="Stack">
|
||
|
|
<link href="Frame-Info.html#Frame-Info" rel="next" title="Frame Info">
|
||
|
|
<link href="Backtrace.html#Backtrace" rel="prev" title="Backtrace">
|
||
|
|
<style type="text/css">
|
||
|
|
<!--
|
||
|
|
a.summary-letter {text-decoration: none}
|
||
|
|
blockquote.indentedblock {margin-right: 0em}
|
||
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
||
|
|
blockquote.smallquotation {font-size: smaller}
|
||
|
|
div.display {margin-left: 3.2em}
|
||
|
|
div.example {margin-left: 3.2em}
|
||
|
|
div.lisp {margin-left: 3.2em}
|
||
|
|
div.smalldisplay {margin-left: 3.2em}
|
||
|
|
div.smallexample {margin-left: 3.2em}
|
||
|
|
div.smalllisp {margin-left: 3.2em}
|
||
|
|
kbd {font-style: oblique}
|
||
|
|
pre.display {font-family: inherit}
|
||
|
|
pre.format {font-family: inherit}
|
||
|
|
pre.menu-comment {font-family: serif}
|
||
|
|
pre.menu-preformatted {font-family: serif}
|
||
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smallexample {font-size: smaller}
|
||
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
||
|
|
pre.smalllisp {font-size: smaller}
|
||
|
|
span.nolinebreak {white-space: nowrap}
|
||
|
|
span.roman {font-family: initial; font-weight: normal}
|
||
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
||
|
|
ul.no-bullet {list-style: none}
|
||
|
|
-->
|
||
|
|
</style>
|
||
|
|
|
||
|
|
|
||
|
|
</head>
|
||
|
|
|
||
|
|
<body lang="en">
|
||
|
|
<a name="Selection"></a>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Frame-Info.html#Frame-Info" accesskey="n" rel="next">Frame Info</a>, Previous: <a href="Backtrace.html#Backtrace" accesskey="p" rel="prev">Backtrace</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>
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<a name="Selecting-a-Frame"></a>
|
||
|
|
<h3 class="section">8.3 Selecting a Frame</h3>
|
||
|
|
|
||
|
|
<p>Most commands for examining the stack and other data in your program work on
|
||
|
|
whichever stack frame is selected at the moment. Here are the commands for
|
||
|
|
selecting a stack frame; all of them finish by printing a brief description
|
||
|
|
of the stack frame just selected.
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dd><a name="index-frame_002c-selecting"></a>
|
||
|
|
<a name="index-f-_0028frame_0029"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>frame <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
|
||
|
|
<dt><code>f <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
|
||
|
|
<dd><p>The <code>frame</code> command allows different stack frames to be
|
||
|
|
selected. The <var>frame-selection-spec</var> can be any of the following:
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dd><a name="index-frame-level-1"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code><var>num</var></code></dt>
|
||
|
|
<dt><code>level <var>num</var></code></dt>
|
||
|
|
<dd><p>Select frame level <var>num</var>. Recall that frame zero is the innermost
|
||
|
|
(currently executing) frame, frame one is the frame that called the
|
||
|
|
innermost one, and so on. The highest level frame is usually the one
|
||
|
|
for <code>main</code>.
|
||
|
|
</p>
|
||
|
|
<p>As this is the most common method of navigating the frame stack, the
|
||
|
|
string <code>level</code> can be omitted. For example, the following two
|
||
|
|
commands are equivalent:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) frame 3
|
||
|
|
(gdb) frame level 3
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<a name="index-frame-address"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>address <var>stack-address</var></code></dt>
|
||
|
|
<dd><p>Select the frame with stack address <var>stack-address</var>. The
|
||
|
|
<var>stack-address</var> for a frame can be seen in the output of
|
||
|
|
<code>info frame</code>, for example:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) info frame
|
||
|
|
Stack level 1, frame at 0x7fffffffda30:
|
||
|
|
rip = 0x40066d in b (amd64-entry-value.cc:59); saved rip 0x4004c5
|
||
|
|
tail call frame, caller of frame at 0x7fffffffda30
|
||
|
|
source language c++.
|
||
|
|
Arglist at unknown address.
|
||
|
|
Locals at unknown address, Previous frame's sp is 0x7fffffffda30
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<p>The <var>stack-address</var> for this frame is <code>0x7fffffffda30</code> as
|
||
|
|
indicated by the line:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">Stack level 1, frame at 0x7fffffffda30:
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<a name="index-frame-function"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>function <var>function-name</var></code></dt>
|
||
|
|
<dd><p>Select the stack frame for function <var>function-name</var>. If there are
|
||
|
|
multiple stack frames for function <var>function-name</var> then the inner
|
||
|
|
most stack frame is selected.
|
||
|
|
</p>
|
||
|
|
<a name="index-frame-view"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>view <var>stack-address</var> <span class="roman">[</span> <var>pc-addr</var> <span class="roman">]</span></code></dt>
|
||
|
|
<dd><p>View a frame that is not part of <small>GDB</small>’s backtrace. The frame
|
||
|
|
viewed has stack address <var>stack-addr</var>, and optionally, a program
|
||
|
|
counter address of <var>pc-addr</var>.
|
||
|
|
</p>
|
||
|
|
<p>This is useful mainly if the chaining of stack frames has been
|
||
|
|
damaged by a bug, making it impossible for <small>GDB</small> to assign
|
||
|
|
numbers properly to all frames. In addition, this can be useful
|
||
|
|
when your program has multiple stacks and switches between them.
|
||
|
|
</p>
|
||
|
|
<p>When viewing a frame outside the current backtrace using
|
||
|
|
<code>frame view</code> then you can always return to the original
|
||
|
|
stack using one of the previous stack frame selection instructions,
|
||
|
|
for example <code>frame level 0</code>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<a name="index-up"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>up <var>n</var></code></dt>
|
||
|
|
<dd><p>Move <var>n</var> frames up the stack; <var>n</var> defaults to 1. For positive
|
||
|
|
numbers <var>n</var>, this advances toward the outermost frame, to higher
|
||
|
|
frame numbers, to frames that have existed longer.
|
||
|
|
</p>
|
||
|
|
<a name="index-down"></a>
|
||
|
|
<a name="index-do-_0028down_0029"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>down <var>n</var></code></dt>
|
||
|
|
<dd><p>Move <var>n</var> frames down the stack; <var>n</var> defaults to 1. For
|
||
|
|
positive numbers <var>n</var>, this advances toward the innermost frame, to
|
||
|
|
lower frame numbers, to frames that were created more recently.
|
||
|
|
You may abbreviate <code>down</code> as <code>do</code>.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>All of these commands end by printing two lines of output describing the
|
||
|
|
frame. The first line shows the frame number, the function name, the
|
||
|
|
arguments, and the source file and line number of execution in that
|
||
|
|
frame. The second line shows the text of that source line.
|
||
|
|
</p>
|
||
|
|
<p>For example:
|
||
|
|
</p>
|
||
|
|
<div class="smallexample">
|
||
|
|
<pre class="smallexample">(gdb) up
|
||
|
|
#1 0x22f0 in main (argc=1, argv=0xf7fffbf4, env=0xf7fffbfc)
|
||
|
|
at env.c:10
|
||
|
|
10 read_input_file (argv[i]);
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<p>After such a printout, the <code>list</code> command with no arguments
|
||
|
|
prints ten lines centered on the point of execution in the frame.
|
||
|
|
You can also edit the program at the point of execution with your favorite
|
||
|
|
editing program by typing <code>edit</code>.
|
||
|
|
See <a href="List.html#List">Printing Source Lines</a>,
|
||
|
|
for details.
|
||
|
|
</p>
|
||
|
|
<dl compact="compact">
|
||
|
|
<dd><a name="index-select_002dframe"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>select-frame <span class="roman">[</span> <var>frame-selection-spec</var> <span class="roman">]</span></code></dt>
|
||
|
|
<dd><p>The <code>select-frame</code> command is a variant of <code>frame</code> that does
|
||
|
|
not display the new frame after selecting it. This command is
|
||
|
|
intended primarily for use in <small>GDB</small> command scripts, where the
|
||
|
|
output might be unnecessary and distracting. The
|
||
|
|
<var>frame-selection-spec</var> is as for the <code>frame</code> command
|
||
|
|
described in <a href="#Selection">Selecting a Frame</a>.
|
||
|
|
</p>
|
||
|
|
<a name="index-down_002dsilently"></a>
|
||
|
|
<a name="index-up_002dsilently"></a>
|
||
|
|
</dd>
|
||
|
|
<dt><code>up-silently <var>n</var></code></dt>
|
||
|
|
<dt><code>down-silently <var>n</var></code></dt>
|
||
|
|
<dd><p>These two commands are variants of <code>up</code> and <code>down</code>,
|
||
|
|
respectively; they differ in that they do their work silently, without
|
||
|
|
causing display of the new frame. They are intended primarily for use
|
||
|
|
in <small>GDB</small> command scripts, where the output might be unnecessary and
|
||
|
|
distracting.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<hr>
|
||
|
|
<div class="header">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Frame-Info.html#Frame-Info" accesskey="n" rel="next">Frame Info</a>, Previous: <a href="Backtrace.html#Backtrace" accesskey="p" rel="prev">Backtrace</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>
|
||
|
|
</div>
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
</body>
|
||
|
|
</html>
|