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diff --git a/share/doc/gdb/Dynamic-Printf.html b/share/doc/gdb/Dynamic-Printf.html new file mode 100644 index 0000000..f916fb9 --- /dev/null +++ b/share/doc/gdb/Dynamic-Printf.html @@ -0,0 +1,200 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 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 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Debugging with GDB: Dynamic Printf</title> + +<meta name="description" content="Debugging with GDB: Dynamic Printf"> +<meta name="keywords" content="Debugging with GDB: Dynamic Printf"> +<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="Breakpoints.html#Breakpoints" rel="up" title="Breakpoints"> +<link href="Save-Breakpoints.html#Save-Breakpoints" rel="next" title="Save Breakpoints"> +<link href="Break-Commands.html#Break-Commands" rel="previous" title="Break Commands"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +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.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Dynamic-Printf"></a> +<div class="header"> +<p> +Next: <a href="Save-Breakpoints.html#Save-Breakpoints" accesskey="n" rel="next">Save Breakpoints</a>, Previous: <a href="Break-Commands.html#Break-Commands" accesskey="p" rel="previous">Break Commands</a>, Up: <a href="Breakpoints.html#Breakpoints" accesskey="u" rel="up">Breakpoints</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="Dynamic-Printf-1"></a> +<h4 class="subsection">5.1.8 Dynamic Printf</h4> + +<a name="index-dynamic-printf"></a> +<a name="index-dprintf"></a> +<p>The dynamic printf command <code>dprintf</code> combines a breakpoint with +formatted printing of your program’s data to give you the effect of +inserting <code>printf</code> calls into your program on-the-fly, without +having to recompile it. +</p> +<p>In its most basic form, the output goes to the GDB console. However, +you can set the variable <code>dprintf-style</code> for alternate handling. +For instance, you can ask to format the output by calling your +program’s <code>printf</code> function. This has the advantage that the +characters go to the program’s output device, so they can recorded in +redirects to files and so forth. +</p> +<p>If you are doing remote debugging with a stub or agent, you can also +ask to have the printf handled by the remote agent. In addition to +ensuring that the output goes to the remote program’s device along +with any other output the program might produce, you can also ask that +the dprintf remain active even after disconnecting from the remote +target. Using the stub/agent is also more efficient, as it can do +everything without needing to communicate with <small>GDB</small>. +</p> +<dl compact="compact"> +<dd><a name="index-dprintf-1"></a> +</dd> +<dt><code>dprintf <var>locspec</var>,<var>template</var>,<var>expression</var>[,<var>expression</var>…]</code></dt> +<dd><p>Whenever execution reaches a code location that results from resolving +<var>locspec</var>, print the values of one or more <var>expressions</var> under +the control of the string <var>template</var>. To print several values, +separate them with commas. +</p> +</dd> +<dt><code>set dprintf-style <var>style</var></code></dt> +<dd><p>Set the dprintf output to be handled in one of several different +styles enumerated below. A change of style affects all existing +dynamic printfs immediately. (If you need individual control over the +print commands, simply define normal breakpoints with +explicitly-supplied command lists.) +</p> +<dl compact="compact"> +<dt><code>gdb</code></dt> +<dd><a name="index-dprintf_002dstyle-gdb"></a> +<p>Handle the output using the <small>GDB</small> <code>printf</code> command. +</p> +</dd> +<dt><code>call</code></dt> +<dd><a name="index-dprintf_002dstyle-call"></a> +<p>Handle the output by calling a function in your program (normally +<code>printf</code>). +</p> +</dd> +<dt><code>agent</code></dt> +<dd><a name="index-dprintf_002dstyle-agent"></a> +<p>Have the remote debugging agent (such as <code>gdbserver</code>) handle +the output itself. This style is only available for agents that +support running commands on the target. +</p></dd> +</dl> + +</dd> +<dt><code>set dprintf-function <var>function</var></code></dt> +<dd><p>Set the function to call if the dprintf style is <code>call</code>. By +default its value is <code>printf</code>. You may set it to any expression. +that <small>GDB</small> can evaluate to a function, as per the <code>call</code> +command. +</p> +</dd> +<dt><code>set dprintf-channel <var>channel</var></code></dt> +<dd><p>Set a “channel” for dprintf. If set to a non-empty value, +<small>GDB</small> will evaluate it as an expression and pass the result as +a first argument to the <code>dprintf-function</code>, in the manner of +<code>fprintf</code> and similar functions. Otherwise, the dprintf format +string will be the first argument, in the manner of <code>printf</code>. +</p> +<p>As an example, if you wanted <code>dprintf</code> output to go to a logfile +that is a standard I/O stream assigned to the variable <code>mylog</code>, +you could do the following: +</p> +<div class="example"> +<pre class="example">(gdb) set dprintf-style call +(gdb) set dprintf-function fprintf +(gdb) set dprintf-channel mylog +(gdb) dprintf 25,"at line 25, glob=%d\n",glob +Dprintf 1 at 0x123456: file main.c, line 25. +(gdb) info break +1 dprintf keep y 0x00123456 in main at main.c:25 + call (void) fprintf (mylog,"at line 25, glob=%d\n",glob) + continue +(gdb) +</pre></div> + +<p>Note that the <code>info break</code> displays the dynamic printf commands +as normal breakpoint commands; you can thus easily see the effect of +the variable settings. +</p> +</dd> +<dt><code>set disconnected-dprintf on</code></dt> +<dt><code>set disconnected-dprintf off</code></dt> +<dd><a name="index-set-disconnected_002ddprintf"></a> +<p>Choose whether <code>dprintf</code> commands should continue to run if +<small>GDB</small> has disconnected from the target. This only applies +if the <code>dprintf-style</code> is <code>agent</code>. +</p> +</dd> +<dt><code>show disconnected-dprintf off</code></dt> +<dd><a name="index-show-disconnected_002ddprintf"></a> +<p>Show the current choice for disconnected <code>dprintf</code>. +</p> +</dd> +</dl> + +<p><small>GDB</small> does not check the validity of function and channel, +relying on you to supply values that are meaningful for the contexts +in which they are being used. For instance, the function and channel +may be the values of local variables, but if that is the case, then +all enabled dynamic prints must be at locations within the scope of +those locals. If evaluation fails, <small>GDB</small> will report an error. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Save-Breakpoints.html#Save-Breakpoints" accesskey="n" rel="next">Save Breakpoints</a>, Previous: <a href="Break-Commands.html#Break-Commands" accesskey="p" rel="previous">Break Commands</a>, Up: <a href="Breakpoints.html#Breakpoints" accesskey="u" rel="up">Breakpoints</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> |