wait3
while ((pid = wait3(&status, WNOHANG, 0)) > 0) {
while (wait3((struct wait *)0, WNOHANG, (struct rusage *)0) > 0)
while (wait3((int *)0, WNOHANG, (struct rusage *)0) > 0)
while ((pid = wait3(&status, WNOHANG, (struct rusage *) NULL)) > 0)
while (wait3(&status.w_status, options, &ru) != p)
extern pid_t wait3(int *, int, struct rusage *);
extern pid_t wait3(int *, int, struct rusage *);