Systerm Time Configuration
query and set the hardware clock (RTC)
hwclock --systohc; hwclock; date
hwclock -r or hwclock --show # read
hwclock -w or hwclock --systohc # write
hwclock -s or hwclock --hctosys # set sys
hwclock -a or hwclock --adjust
hwclock -v or hwclock --version
hwclock --set --date=newdate
hwclock --getepoch
hwclock --setepoch --epoch=year