sysbeep
sysbeep(500, SBT_1S);
sysbeep(500, SBT_1S);
sysbeep((time_second % 5) * 100 + 500, SBT_1S / 8);
sysbeep(1193182 / pitch, SBT_1S * duration / hz);
sysbeep(vw->vw_bell_pitch, vw->vw_bell_duration);
sysbeep(freq, period);
sysbeep(880, SBT_1S);
sysbeep(880, SBT_1S);
SYSINIT(sysbeep, SI_SUB_SOFTINTR, SI_ORDER_ANY, sysbeep_init, NULL);
int sysbeep(int hertz, sbintime_t duration);