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5.1 KiB
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101 lines
5.1 KiB
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<html lang="en">
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<head>
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<title>Attach - Debugging with GDB</title>
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<meta name="description" content="Debugging with GDB">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="Running.html#Running" title="Running">
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<link rel="prev" href="Input_002fOutput.html#Input_002fOutput" title="Input/Output">
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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<body>
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<div class="node">
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<a name="Attach"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="Kill-Process.html#Kill-Process">Kill Process</a>,
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Previous: <a rel="previous" accesskey="p" href="Input_002fOutput.html#Input_002fOutput">Input/Output</a>,
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Up: <a rel="up" accesskey="u" href="Running.html#Running">Running</a>
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<hr>
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</div>
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<h3 class="section">4.7 Debugging an Already-running Process</h3>
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<p><a name="index-attach-153"></a><a name="index-attach-154"></a>
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<dl>
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<dt><code>attach </code><var>process-id</var><dd>This command attaches to a running process—one that was started
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outside <span class="sc">gdb</span>. (<code>info files</code> shows your active
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targets.) The command takes as argument a process ID. The usual way to
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find out the <var>process-id</var> of a Unix process is with the <code>ps</code> utility,
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or with the ‘<samp><span class="samp">jobs -l</span></samp>’ shell command.
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<p><code>attach</code> does not repeat if you press <RET> a second time after
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executing the command.
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</dl>
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<p>To use <code>attach</code>, your program must be running in an environment
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which supports processes; for example, <code>attach</code> does not work for
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programs on bare-board targets that lack an operating system. You must
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also have permission to send the process a signal.
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<p>When you use <code>attach</code>, the debugger finds the program running in
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the process first by looking in the current working directory, then (if
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the program is not found) by using the source file search path
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(see <a href="Source-Path.html#Source-Path">Specifying Source Directories</a>). You can also use
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the <code>file</code> command to load the program. See <a href="Files.html#Files">Commands to Specify Files</a>.
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<p>The first thing <span class="sc">gdb</span> does after arranging to debug the specified
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process is to stop it. You can examine and modify an attached process
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with all the <span class="sc">gdb</span> commands that are ordinarily available when
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you start processes with <code>run</code>. You can insert breakpoints; you
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can step and continue; you can modify storage. If you would rather the
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process continue running, you may use the <code>continue</code> command after
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attaching <span class="sc">gdb</span> to the process.
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<a name="index-detach-155"></a>
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<dl><dt><code>detach</code><dd>When you have finished debugging the attached process, you can use the
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<code>detach</code> command to release it from <span class="sc">gdb</span> control. Detaching
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the process continues its execution. After the <code>detach</code> command,
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that process and <span class="sc">gdb</span> become completely independent once more, and you
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are ready to <code>attach</code> another process or start one with <code>run</code>.
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<code>detach</code> does not repeat if you press <RET> again after
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executing the command.
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</dl>
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<p>If you exit <span class="sc">gdb</span> while you have an attached process, you detach
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that process. If you use the <code>run</code> command, you kill that process.
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By default, <span class="sc">gdb</span> asks for confirmation if you try to do either of these
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things; you can control whether or not you need to confirm by using the
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<code>set confirm</code> command (see <a href="Messages_002fWarnings.html#Messages_002fWarnings">Optional Warnings and Messages</a>).
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</body></html>
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