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17<title>Debugging with GDB: Interpreters</title>
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64<a name="Interpreters"></a>
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66<p>
67Next: <a href="TUI.html#TUI" accesskey="n" rel="next">TUI</a>, Previous: <a href="Extending-GDB.html#Extending-GDB" accesskey="p" rel="previous">Extending GDB</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</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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70<a name="Command-Interpreters"></a>
71<h2 class="chapter">24 Command Interpreters</h2>
72<a name="index-command-interpreters"></a>
73
74<p><small>GDB</small> supports multiple command interpreters, and some command
75infrastructure to allow users or user interface writers to switch
76between interpreters or run commands in other interpreters.
77</p>
78<p><small>GDB</small> currently supports two command interpreters, the console
79interpreter (sometimes called the command-line interpreter or <small>CLI</small>)
80and the machine interface interpreter (or <small>GDB/MI</small>).  This manual
81describes both of these interfaces in great detail.
82</p>
83<p>By default, <small>GDB</small> will start with the console interpreter.
84However, the user may choose to start <small>GDB</small> with another
85interpreter by specifying the <samp>-i</samp> or <samp>--interpreter</samp>
86startup options.  Defined interpreters include:
87</p>
88<dl compact="compact">
89<dt><code>console</code></dt>
90<dd><a name="index-console-interpreter"></a>
91<p>The traditional console or command-line interpreter.  This is the most often
92used interpreter with <small>GDB</small>. With no interpreter specified at runtime,
93<small>GDB</small> will use this interpreter.
94</p>
95</dd>
96<dt><code>mi</code></dt>
97<dd><a name="index-mi-interpreter"></a>
98<p>The newest <small>GDB/MI</small> interface (currently <code>mi3</code>).  Used primarily
99by programs wishing to use <small>GDB</small> as a backend for a debugger GUI
100or an IDE.  For more information, see <a href="GDB_002fMI.html#GDB_002fMI">The <small>GDB/MI</small>
101Interface</a>.
102</p>
103</dd>
104<dt><code>mi3</code></dt>
105<dd><a name="index-mi3-interpreter"></a>
106<p>The <small>GDB/MI</small> interface introduced in <small>GDB</small> 9.1.
107</p>
108</dd>
109<dt><code>mi2</code></dt>
110<dd><a name="index-mi2-interpreter"></a>
111<p>The <small>GDB/MI</small> interface introduced in <small>GDB</small> 6.0.
112</p>
113</dd>
114<dt><code>mi1</code></dt>
115<dd><a name="index-mi1-interpreter"></a>
116<p>The <small>GDB/MI</small> interface introduced in <small>GDB</small> 5.1.
117</p>
118</dd>
119</dl>
120
121<a name="index-invoke-another-interpreter"></a>
122
123<a name="index-interpreter_002dexec"></a>
124<p>You may execute commands in any interpreter from the current
125interpreter using the appropriate command.  If you are running the
126console interpreter, simply use the <code>interpreter-exec</code> command:
127</p>
128<div class="smallexample">
129<pre class="smallexample">interpreter-exec mi &quot;-data-list-register-names&quot;
130</pre></div>
131
132<p><small>GDB/MI</small> has a similar command, although it is only available in versions of
133<small>GDB</small> which support <small>GDB/MI</small> version 2 (or greater).
134</p>
135<p>Note that <code>interpreter-exec</code> only changes the interpreter for the
136duration of the specified command.  It does not change the interpreter
137permanently.
138</p>
139<a name="index-start-a-new-independent-interpreter"></a>
140
141<p>Although you may only choose a single interpreter at startup, it is
142possible to run an independent interpreter on a specified input/output
143device (usually a tty).
144</p>
145<p>For example, consider a debugger GUI or IDE that wants to provide a
146<small>GDB</small> console view.  It may do so by embedding a terminal
147emulator widget in its GUI, starting <small>GDB</small> in the traditional
148command-line mode with stdin/stdout/stderr redirected to that
149terminal, and then creating an MI interpreter running on a specified
150input/output device.  The console interpreter created by <small>GDB</small>
151at startup handles commands the user types in the terminal widget,
152while the GUI controls and synchronizes state with <small>GDB</small> using
153the separate MI interpreter.
154</p>
155<p>To start a new secondary <em>user interface</em> running MI, use the
156<code>new-ui</code> command:
157</p>
158<a name="index-new_002dui"></a>
159<a name="index-new-user-interface"></a>
160<div class="smallexample">
161<pre class="smallexample">new-ui <var>interpreter</var> <var>tty</var>
162</pre></div>
163
164<p>The <var>interpreter</var> parameter specifies the interpreter to run.
165This accepts the same values as the <code>interpreter-exec</code> command.
166For example, &lsquo;<samp>console</samp>&rsquo;, &lsquo;<samp>mi</samp>&rsquo;, &lsquo;<samp>mi2</samp>&rsquo;, etc.  The
167<var>tty</var> parameter specifies the name of the bidirectional file the
168interpreter uses for input/output, usually the name of a
169pseudoterminal slave on Unix systems.  For example:
170</p>
171<div class="smallexample">
172<pre class="smallexample">(gdb) new-ui mi /dev/pts/9
173</pre></div>
174
175<p>runs an MI interpreter on <samp>/dev/pts/9</samp>.
176</p>
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