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| <h4 class="subsection">24.8.1 Using <code>pause</code></h4> |
| |
| <p>The simple way to wait until a signal arrives is to call <code>pause</code>. |
| Please read about its disadvantages, in the following section, before |
| you use it. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Function: int <b>pause</b> ()<var><a name="index-pause-2981"></a></var><br> |
| <blockquote><p>The <code>pause</code> function suspends program execution until a signal |
| arrives whose action is either to execute a handler function, or to |
| terminate the process. |
| |
| <p>If the signal causes a handler function to be executed, then |
| <code>pause</code> returns. This is considered an unsuccessful return (since |
| “successful” behavior would be to suspend the program forever), so the |
| return value is <code>-1</code>. Even if you specify that other primitives |
| should resume when a system handler returns (see <a href="Interrupted-Primitives.html#Interrupted-Primitives">Interrupted Primitives</a>), this has no effect on <code>pause</code>; it always fails when a |
| signal is handled. |
| |
| <p>The following <code>errno</code> error conditions are defined for this function: |
| |
| <dl> |
| <dt><code>EINTR</code><dd>The function was interrupted by delivery of a signal. |
| </dl> |
| |
| <p>If the signal causes program termination, <code>pause</code> doesn't return |
| (obviously). |
| |
| <p>This function is a cancellation point in multithreaded programs. This |
| is a problem if the thread allocates some resources (like memory, file |
| descriptors, semaphores or whatever) at the time <code>pause</code> is |
| called. If the thread gets cancelled these resources stay allocated |
| until the program ends. To avoid this calls to <code>pause</code> should be |
| protected using cancellation handlers. |
| <!-- ref pthread_cleanup_push / pthread_cleanup_pop --> |
| |
| <p>The <code>pause</code> function is declared in <samp><span class="file">unistd.h</span></samp>. |
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