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| <h3 class="section">4.7 Debugging an Already-running Process</h3> |
| |
| <p><a name="index-attach-133"></a><a name="index-attach-134"></a> |
| <dl> |
| <dt><code>attach </code><var>process-id</var><dd>This command attaches to a running process—one that was started |
| outside <span class="sc">gdb</span>. (<code>info files</code> shows your active |
| targets.) The command takes as argument a process ID. The usual way to |
| find out the <var>process-id</var> of a Unix process is with the <code>ps</code> utility, |
| or with the ‘<samp><span class="samp">jobs -l</span></samp>’ shell command. |
| |
| <p><code>attach</code> does not repeat if you press <RET> a second time after |
| executing the command. |
| </dl> |
| |
| <p>To use <code>attach</code>, your program must be running in an environment |
| which supports processes; for example, <code>attach</code> does not work for |
| programs on bare-board targets that lack an operating system. You must |
| also have permission to send the process a signal. |
| |
| <p>When you use <code>attach</code>, the debugger finds the program running in |
| the process first by looking in the current working directory, then (if |
| the program is not found) by using the source file search path |
| (see <a href="Source-Path.html#Source-Path">Specifying Source Directories</a>). You can also use |
| the <code>file</code> command to load the program. See <a href="Files.html#Files">Commands to Specify Files</a>. |
| |
| <p>The first thing <span class="sc">gdb</span> does after arranging to debug the specified |
| process is to stop it. You can examine and modify an attached process |
| with all the <span class="sc">gdb</span> commands that are ordinarily available when |
| you start processes with <code>run</code>. You can insert breakpoints; you |
| can step and continue; you can modify storage. If you would rather the |
| process continue running, you may use the <code>continue</code> command after |
| attaching <span class="sc">gdb</span> to the process. |
| |
| |
| <a name="index-detach-135"></a> |
| <dl><dt><code>detach</code><dd>When you have finished debugging the attached process, you can use the |
| <code>detach</code> command to release it from <span class="sc">gdb</span> control. Detaching |
| the process continues its execution. After the <code>detach</code> command, |
| that process and <span class="sc">gdb</span> become completely independent once more, and you |
| are ready to <code>attach</code> another process or start one with <code>run</code>. |
| <code>detach</code> does not repeat if you press <RET> again after |
| executing the command. |
| </dl> |
| |
| <p>If you exit <span class="sc">gdb</span> while you have an attached process, you detach |
| that process. If you use the <code>run</code> command, you kill that process. |
| By default, <span class="sc">gdb</span> asks for confirmation if you try to do either of these |
| things; you can control whether or not you need to confirm by using the |
| <code>set confirm</code> command (see <a href="Messages_002fWarnings.html#Messages_002fWarnings">Optional Warnings and Messages</a>). |
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