date --set="23 June 1988 10:00:00"
date --set="10:00:00"

Set the Hardware Clock to the current System Time
# hwclock --systohc

Set the System Time from the Hardware Clock.
# hwclock --hctosys

via ntpd

sudo service ntp stop
sudo ntpd -gq
sudo service ntp start

via ntpdate

ntpdate ntp.ubuntu.com

如果出現 Server dropped: strata too high，在 ntp.conf 新增以下

server 127.127.1.0
fudge 127.127.1.0 stratum 8

參考

• http://superuser.com/questions/302396/how-to-set-current-time-on-linux
• http://askubuntu.com/questions/254826/how-to-force-a-clock-update-using-ntp
• http://superuser.com/questions/181341/how-to-check-if-ntp-adjusted-system-time-on-linux