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| <h4 class="subsection">5.4.3 Background Execution</h4> |
| |
| <p><a name="index-foreground-execution-329"></a><a name="index-background-execution-330"></a><a name="index-asynchronous-execution-331"></a><a name="index-execution_002c-foreground_002c-background-and-asynchronous-332"></a> |
| <span class="sc">gdb</span>'s execution commands have two variants: the normal |
| foreground (synchronous) behavior, and a background |
| (asynchronous) behavior. In foreground execution, <span class="sc">gdb</span> waits for |
| the program to report that some thread has stopped before prompting for |
| another command. In background execution, <span class="sc">gdb</span> immediately gives |
| a command prompt so that you can issue other commands while your program runs. |
| |
| <p>You need to explicitly enable asynchronous mode before you can use |
| background execution commands. You can use these commands to |
| manipulate the asynchronous mode setting: |
| |
| |
| <a name="index-set-target_002dasync-333"></a> |
| <dl><dt><code>set target-async on</code><dd>Enable asynchronous mode. |
| <br><dt><code>set target-async off</code><dd>Disable asynchronous mode. |
| <a name="index-show-target_002dasync-334"></a><br><dt><code>show target-async</code><dd>Show the current target-async setting. |
| </dl> |
| |
| <p>If the target doesn't support async mode, <span class="sc">gdb</span> issues an error |
| message if you attempt to use the background execution commands. |
| |
| <p>To specify background execution, add a <code>&</code> to the command. For example, |
| the background form of the <code>continue</code> command is <code>continue&</code>, or |
| just <code>c&</code>. The execution commands that accept background execution |
| are: |
| |
| |
| <a name="index-run_0026-335"></a> |
| <dl><dt><code>run</code><dd>See <a href="Starting.html#Starting">Starting your Program</a>. |
| |
| <br><dt><code>attach</code><dd><a name="index-attach_0026-336"></a>See <a href="Attach.html#Attach">Debugging an Already-running Process</a>. |
| |
| <br><dt><code>step</code><dd><a name="index-step_0026-337"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">step</a>. |
| |
| <br><dt><code>stepi</code><dd><a name="index-stepi_0026-338"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">stepi</a>. |
| |
| <br><dt><code>next</code><dd><a name="index-next_0026-339"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">next</a>. |
| |
| <br><dt><code>nexti</code><dd><a name="index-nexti_0026-340"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">nexti</a>. |
| |
| <br><dt><code>continue</code><dd><a name="index-continue_0026-341"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">continue</a>. |
| |
| <br><dt><code>finish</code><dd><a name="index-finish_0026-342"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">finish</a>. |
| |
| <br><dt><code>until</code><dd><a name="index-until_0026-343"></a>See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">until</a>. |
| |
| </dl> |
| |
| <p>Background execution is especially useful in conjunction with non-stop |
| mode for debugging programs with multiple threads; see <a href="Non_002dStop-Mode.html#Non_002dStop-Mode">Non-Stop Mode</a>. |
| However, you can also use these commands in the normal all-stop mode with |
| the restriction that you cannot issue another execution command until the |
| previous one finishes. Examples of commands that are valid in all-stop |
| mode while the program is running include <code>help</code> and <code>info break</code>. |
| |
| <p>You can interrupt your program while it is running in the background by |
| using the <code>interrupt</code> command. |
| |
| |
| <a name="index-interrupt-344"></a> |
| <dl><dt><code>interrupt</code><dt><code>interrupt -a</code><dd> |
| Suspend execution of the running program. In all-stop mode, |
| <code>interrupt</code> stops the whole process, but in non-stop mode, it stops |
| only the current thread. To stop the whole program in non-stop mode, |
| use <code>interrupt -a</code>. |
| </dl> |
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