BSD Wait Functions (The GNU C Library)

### 27.9 BSD Process Wait Function ¶

The GNU C Library also provides the `wait3` function for compatibility with BSD. This function is declared in `sys/wait.h`. It is the predecessor to `wait4`, which is more flexible. `wait3` is now obsolete.

Function: `pid_t` wait3 `(int *status-ptr, int options, struct rusage *usage)` ¶

  Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

  If usage is a null pointer, `wait3` is equivalent to `waitpid (-1, status-ptr, options)`.

  If usage is not null, `wait3` stores usage figures for the child process in `*rusage` (but only if the child has terminated, not if it has stopped). See Resource Usage.