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| <h3 class="section">26.8 BSD Process Wait Functions</h3> |
| |
| <p>The GNU library also provides these related facilities for compatibility |
| with BSD Unix. BSD uses the <code>union wait</code> data type to represent |
| status values rather than an <code>int</code>. The two representations are |
| actually interchangeable; they describe the same bit patterns. The GNU |
| C Library defines macros such as <code>WEXITSTATUS</code> so that they will |
| work on either kind of object, and the <code>wait</code> function is defined |
| to accept either type of pointer as its <var>status-ptr</var> argument. |
| |
| <p>These functions are declared in <samp><span class="file">sys/wait.h</span></samp>. |
| <a name="index-sys_002fwait_002eh-3193"></a> |
| <!-- sys/wait.h --> |
| <!-- BSD --> |
| |
| <div class="defun"> |
| — Data Type: <b>union wait</b><var><a name="index-union-wait-3194"></a></var><br> |
| <blockquote><p>This data type represents program termination status values. It has |
| the following members: |
| |
| <dl> |
| <dt><code>int w_termsig</code><dd>The value of this member is the same as that of the |
| <code>WTERMSIG</code> macro. |
| |
| <br><dt><code>int w_coredump</code><dd>The value of this member is the same as that of the |
| <code>WCOREDUMP</code> macro. |
| |
| <br><dt><code>int w_retcode</code><dd>The value of this member is the same as that of the |
| <code>WEXITSTATUS</code> macro. |
| |
| <br><dt><code>int w_stopsig</code><dd>The value of this member is the same as that of the |
| <code>WSTOPSIG</code> macro. |
| </dl> |
| |
| <p>Instead of accessing these members directly, you should use the |
| equivalent macros. |
| </p></blockquote></div> |
| |
| <p>The <code>wait3</code> function is the predecessor to <code>wait4</code>, which is |
| more flexible. <code>wait3</code> is now obsolete. |
| |
| <!-- sys/wait.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: pid_t <b>wait3</b> (<var>union wait *status-ptr, int options, struct rusage *usage</var>)<var><a name="index-wait3-3195"></a></var><br> |
| <blockquote><p>If <var>usage</var> is a null pointer, <code>wait3</code> is equivalent to |
| <code>waitpid (-1, </code><var>status-ptr</var><code>, </code><var>options</var><code>)</code>. |
| |
| <p>If <var>usage</var> is not null, <code>wait3</code> stores usage figures for the |
| child process in <code>*</code><var>rusage</var> (but only if the child has |
| terminated, not if it has stopped). See <a href="Resource-Usage.html#Resource-Usage">Resource Usage</a>. |
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