To disable the system beep during the shutdown -h +time, sysfinit has to be downloaded into your machine.
apt-get source sysvinit
then find a “
void warn(int mins)” function and there change
wall(buf, 0); to
then run ./configure make etc. or make a package. Also you can use this:
Surely there is another way to off the beep which I do not know 😉