sigwait
int sigwait(const sigset_t *__restrict, int *__restrict);
PROTO_DEPRECATED(sigwait);
CHECKr(sigwait(&sigusr2, &r));
CHECKr(sigwait(&mask, &sig));
CHECKe(sigwait (&wait_mask, &signo));
if (sigwait(&set, &sig) != 0)