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<h3 class="heading">gdbserver man</h3>
<!-- man title gdbserver Remote Server for the GNU Debugger -->
<pre class="format"><!-- man begin SYNOPSIS gdbserver -->
gdbserver <var>comm</var> <var>prog</var> [<var>args</var><small class="dots">...</small>]
gdbserver &ndash;attach <var>comm</var> <var>pid</var>
gdbserver &ndash;multi <var>comm</var>
<!-- man end -->
</pre>
<!-- man begin DESCRIPTION gdbserver -->
<p><samp><span class="command">gdbserver</span></samp> is a program that allows you to run <span class="sc">gdb</span> on a different machine
than the one which is running the program being debugged.
<h4 class="subheading">Usage (server (target) side)</h4>
<p>First, you need to have a copy of the program you want to debug put onto
the target system. The program can be stripped to save space if needed, as
<samp><span class="command">gdbserver</span></samp> doesn't care about symbols. All symbol handling is taken care of by
the <span class="sc">gdb</span> running on the host system.
<p>To use the server, you log on to the target system, and run the <samp><span class="command">gdbserver</span></samp>
program. You must tell it (a) how to communicate with <span class="sc">gdb</span>, (b) the name of
your program, and (c) its arguments. The general syntax is:
<pre class="smallexample"> target&gt; gdbserver <var>comm</var> <var>program</var> [<var>args</var> ...]
</pre>
<p>For example, using a serial port, you might say:
<pre class="smallexample"> target&gt; gdbserver <samp><span class="file">/dev/com1</span></samp> emacs foo.txt
</pre>
<p>This tells <samp><span class="command">gdbserver</span></samp> to debug emacs with an argument of foo.txt, and
to communicate with <span class="sc">gdb</span> via <samp><span class="file">/dev/com1</span></samp>. <samp><span class="command">gdbserver</span></samp> now
waits patiently for the host <span class="sc">gdb</span> to communicate with it.
<p>To use a TCP connection, you could say:
<pre class="smallexample"> target&gt; gdbserver host:2345 emacs foo.txt
</pre>
<p>This says pretty much the same thing as the last example, except that we are
going to communicate with the <code>host</code> <span class="sc">gdb</span> via TCP. The <code>host:2345</code> argument means
that we are expecting to see a TCP connection from <code>host</code> to local TCP port
2345. (Currently, the <code>host</code> part is ignored.) You can choose any number you
want for the port number as long as it does not conflict with any existing TCP
ports on the target system. This same port number must be used in the host
<span class="sc">gdb</span>s <code>target remote</code> command, which will be described shortly. Note that if
you chose a port number that conflicts with another service, <samp><span class="command">gdbserver</span></samp> will
print an error message and exit.
<p><samp><span class="command">gdbserver</span></samp> can also attach to running programs.
This is accomplished via the <samp><span class="option">--attach</span></samp> argument. The syntax is:
<pre class="smallexample"> target&gt; gdbserver --attach <var>comm</var> <var>pid</var>
</pre>
<p><var>pid</var> is the process ID of a currently running process. It isn't
necessary to point <samp><span class="command">gdbserver</span></samp> at a binary for the running process.
<p>To start <code>gdbserver</code> without supplying an initial command to run
or process ID to attach, use the <samp><span class="option">--multi</span></samp> command line option.
In such case you should connect using <kbd>target extended-remote</kbd> to start
the program you want to debug.
<pre class="smallexample"> target&gt; gdbserver --multi <var>comm</var>
</pre>
<h4 class="subheading">Usage (host side)</h4>
<p>You need an unstripped copy of the target program on your host system, since
<span class="sc">gdb</span> needs to examine its symbol tables and such. Start up <span class="sc">gdb</span> as you normally
would, with the target program as the first argument. (You may need to use the
<samp><span class="option">--baud</span></samp> option if the serial line is running at anything except 9600 baud.)
That is <code>gdb TARGET-PROG</code>, or <code>gdb --baud BAUD TARGET-PROG</code>. After that, the only
new command you need to know about is <code>target remote</code>
(or <code>target extended-remote</code>). Its argument is either
a device name (usually a serial device, like <samp><span class="file">/dev/ttyb</span></samp>), or a <code>HOST:PORT</code>
descriptor. For example:
<pre class="smallexample"> (gdb) target remote <samp><span class="file">/dev/ttyb</span></samp>
</pre>
<p class="noindent">communicates with the server via serial line <samp><span class="file">/dev/ttyb</span></samp>, and:
<pre class="smallexample"> (gdb) target remote the-target:2345
</pre>
<p class="noindent">communicates via a TCP connection to port 2345 on host `the-target', where
you previously started up <samp><span class="command">gdbserver</span></samp> with the same port number. Note that for
TCP connections, you must start up <samp><span class="command">gdbserver</span></samp> prior to using the `target remote'
command, otherwise you may get an error that looks something like
`Connection refused'.
<p><samp><span class="command">gdbserver</span></samp> can also debug multiple inferiors at once,
described in
<a href="Inferiors-and-Programs.html#Inferiors-and-Programs">Inferiors and Programs</a>.
In such case use the <code>extended-remote</code> <span class="sc">gdb</span> command variant:
<pre class="smallexample"> (gdb) target extended-remote the-target:2345
</pre>
<p>The <samp><span class="command">gdbserver</span></samp> option <samp><span class="option">--multi</span></samp> may or may not be used in such
case.
<!-- man end -->
<!-- man begin OPTIONS gdbserver -->
<p>There are three different modes for invoking <samp><span class="command">gdbserver</span></samp>:
<ul>
<li>Debug a specific program specified by its program name:
<pre class="smallexample"> gdbserver <var>comm</var> <var>prog</var> [<var>args</var>...]
</pre>
<p>The <var>comm</var> parameter specifies how should the server communicate
with <span class="sc">gdb</span>; it is either a device name (to use a serial line),
a TCP port number (<code>:1234</code>), or <code>-</code> or <code>stdio</code> to use
stdin/stdout of <code>gdbserver</code>. Specify the name of the program to
debug in <var>prog</var>. Any remaining arguments will be passed to the
program verbatim. When the program exits, <span class="sc">gdb</span> will close the
connection, and <code>gdbserver</code> will exit.
<li>Debug a specific program by specifying the process ID of a running
program:
<pre class="smallexample"> gdbserver --attach <var>comm</var> <var>pid</var>
</pre>
<p>The <var>comm</var> parameter is as described above. Supply the process ID
of a running program in <var>pid</var>; <span class="sc">gdb</span> will do everything
else. Like with the previous mode, when the process <var>pid</var> exits,
<span class="sc">gdb</span> will close the connection, and <code>gdbserver</code> will exit.
<li>Multi-process mode &ndash; debug more than one program/process:
<pre class="smallexample"> gdbserver --multi <var>comm</var>
</pre>
<p>In this mode, <span class="sc">gdb</span> can instruct <samp><span class="command">gdbserver</span></samp> which
command(s) to run. Unlike the other 2 modes, <span class="sc">gdb</span> will not
close the connection when a process being debugged exits, so you can
debug several processes in the same session.
</ul>
<p>In each of the modes you may specify these options:
<dl>
<dt><samp><span class="env">--help</span></samp><dd>List all options, with brief explanations.
<br><dt><samp><span class="env">--version</span></samp><dd>This option causes <samp><span class="command">gdbserver</span></samp> to print its version number and exit.
<br><dt><samp><span class="env">--attach</span></samp><dd><samp><span class="command">gdbserver</span></samp> will attach to a running program. The syntax is:
<pre class="smallexample"> target&gt; gdbserver --attach <var>comm</var> <var>pid</var>
</pre>
<p><var>pid</var> is the process ID of a currently running process. It isn't
necessary to point <samp><span class="command">gdbserver</span></samp> at a binary for the running process.
<br><dt><samp><span class="env">--multi</span></samp><dd>To start <code>gdbserver</code> without supplying an initial command to run
or process ID to attach, use this command line option.
Then you can connect using <kbd>target extended-remote</kbd> and start
the program you want to debug. The syntax is:
<pre class="smallexample"> target&gt; gdbserver --multi <var>comm</var>
</pre>
<br><dt><samp><span class="env">--debug</span></samp><dd>Instruct <code>gdbserver</code> to display extra status information about the debugging
process.
This option is intended for <code>gdbserver</code> development and for bug reports to
the developers.
<br><dt><samp><span class="env">--remote-debug</span></samp><dd>Instruct <code>gdbserver</code> to display remote protocol debug output.
This option is intended for <code>gdbserver</code> development and for bug reports to
the developers.
<br><dt><samp><span class="env">--debug-format=option1[,option2,...]</span></samp><dd>Instruct <code>gdbserver</code> to include extra information in each line
of debugging output.
See <a href="Other-Command_002dLine-Arguments-for-gdbserver.html#Other-Command_002dLine-Arguments-for-gdbserver">Other Command-Line Arguments for gdbserver</a>.
<br><dt><samp><span class="env">--wrapper</span></samp><dd>Specify a wrapper to launch programs
for debugging. The option should be followed by the name of the
wrapper, then any command-line arguments to pass to the wrapper, then
<kbd>--</kbd> indicating the end of the wrapper arguments.
<br><dt><samp><span class="env">--once</span></samp><dd>By default, <samp><span class="command">gdbserver</span></samp> keeps the listening TCP port open, so that
additional connections are possible. However, if you start <code>gdbserver</code>
with the <samp><span class="option">--once</span></samp> option, it will stop listening for any further
connection attempts after connecting to the first <span class="sc">gdb</span> session.
<!-- disable-packet is not documented for users. -->
<!-- disable-randomization and -no-disable-randomization are superseded by -->
<!-- QDisableRandomization. -->
</dl>
<!-- man end -->
<!-- man begin SEEALSO gdbserver -->
<!-- man end -->
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