| <html lang="en"> |
| <head> |
| <title>Define - Debugging with GDB</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Debugging with GDB"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Sequences.html#Sequences" title="Sequences"> |
| <link rel="next" href="Hooks.html#Hooks" title="Hooks"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, |
| 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 |
| 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.''--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Define"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Hooks.html#Hooks">Hooks</a>, |
| Up: <a rel="up" accesskey="u" href="Sequences.html#Sequences">Sequences</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">23.1.1 User-defined Commands</h4> |
| |
| <p><a name="index-user_002ddefined-command-1531"></a><a name="index-arguments_002c-to-user_002ddefined-commands-1532"></a>A <dfn>user-defined command</dfn> is a sequence of <span class="sc">gdb</span> commands to |
| which you assign a new name as a command. This is done with the |
| <code>define</code> command. User commands may accept up to 10 arguments |
| separated by whitespace. Arguments are accessed within the user command |
| via <code>$arg0...$arg9</code>. A trivial example: |
| |
| <pre class="smallexample"> define adder |
| print $arg0 + $arg1 + $arg2 |
| end |
| </pre> |
| <p class="noindent">To execute the command use: |
| |
| <pre class="smallexample"> adder 1 2 3 |
| </pre> |
| <p class="noindent">This defines the command <code>adder</code>, which prints the sum of |
| its three arguments. Note the arguments are text substitutions, so they may |
| reference variables, use complex expressions, or even perform inferior |
| functions calls. |
| |
| <p><a name="index-argument-count-in-user_002ddefined-commands-1533"></a><a name="index-how-many-arguments-_0028user_002ddefined-commands_0029-1534"></a>In addition, <code>$argc</code> may be used to find out how many arguments have |
| been passed. This expands to a number in the range 0<small class="dots">...</small>10. |
| |
| <pre class="smallexample"> define adder |
| if $argc == 2 |
| print $arg0 + $arg1 |
| end |
| if $argc == 3 |
| print $arg0 + $arg1 + $arg2 |
| end |
| end |
| </pre> |
| |
| <a name="index-define-1535"></a> |
| <dl><dt><code>define </code><var>commandname</var><dd>Define a command named <var>commandname</var>. If there is already a command |
| by that name, you are asked to confirm that you want to redefine it. |
| <var>commandname</var> may be a bare command name consisting of letters, |
| numbers, dashes, and underscores. It may also start with any predefined |
| prefix command. For example, ‘<samp><span class="samp">define target my-target</span></samp>’ creates |
| a user-defined ‘<samp><span class="samp">target my-target</span></samp>’ command. |
| |
| <p>The definition of the command is made up of other <span class="sc">gdb</span> command lines, |
| which are given following the <code>define</code> command. The end of these |
| commands is marked by a line containing <code>end</code>. |
| |
| <p><a name="index-document-1536"></a><a name="index-end_0040r_007b-_0028user_002ddefined-commands_0029_007d-1537"></a><br><dt><code>document </code><var>commandname</var><dd>Document the user-defined command <var>commandname</var>, so that it can be |
| accessed by <code>help</code>. The command <var>commandname</var> must already be |
| defined. This command reads lines of documentation just as <code>define</code> |
| reads the lines of the command definition, ending with <code>end</code>. |
| After the <code>document</code> command is finished, <code>help</code> on command |
| <var>commandname</var> displays the documentation you have written. |
| |
| <p>You may use the <code>document</code> command again to change the |
| documentation of a command. Redefining the command with <code>define</code> |
| does not change the documentation. |
| |
| <p><a name="index-dont_002drepeat-1538"></a><a name="index-don_0027t-repeat-command-1539"></a><br><dt><code>dont-repeat</code><dd>Used inside a user-defined command, this tells <span class="sc">gdb</span> that this |
| command should not be repeated when the user hits <RET> |
| (see <a href="Command-Syntax.html#Command-Syntax">repeat last command</a>). |
| |
| <p><a name="index-help-user_002ddefined-1540"></a><br><dt><code>help user-defined</code><dd>List all user-defined commands, with the first line of the documentation |
| (if any) for each. |
| |
| <p><a name="index-show-user-1541"></a><br><dt><code>show user</code><dt><code>show user </code><var>commandname</var><dd>Display the <span class="sc">gdb</span> commands used to define <var>commandname</var> (but |
| not its documentation). If no <var>commandname</var> is given, display the |
| definitions for all user-defined commands. |
| |
| <p><a name="index-infinite-recursion-in-user_002ddefined-commands-1542"></a><a name="index-show-max_002duser_002dcall_002ddepth-1543"></a><a name="index-set-max_002duser_002dcall_002ddepth-1544"></a><br><dt><code>show max-user-call-depth</code><dt><code>set max-user-call-depth</code><dd>The value of <code>max-user-call-depth</code> controls how many recursion |
| levels are allowed in user-defined commands before <span class="sc">gdb</span> suspects an |
| infinite recursion and aborts the command. |
| </dl> |
| |
| <p>In addition to the above commands, user-defined commands frequently |
| use control flow commands, described in <a href="Command-Files.html#Command-Files">Command Files</a>. |
| |
| <p>When user-defined commands are executed, the |
| commands of the definition are not printed. An error in any command |
| stops execution of the user-defined command. |
| |
| <p>If used interactively, commands that would ask for confirmation proceed |
| without asking when used inside a user-defined command. Many <span class="sc">gdb</span> |
| commands that normally print messages to say what they are doing omit the |
| messages when used in a user-defined command. |
| |
| </body></html> |
| |
