Set/show date and time
date +%T
date +%T -s 15:40:00
where %T is format string
However, I was forced to set up time in BIOS

yes but here comes hwclock to play
we keep date in our computer clock utc so

1. make sure your time zone is setup properly	tzconfig
2. set up system time and date properly		date +%??? -s ???
3. write it to hwclock with:			hwclock --utc --systohc