General Command-ntpdate

#sudo ntpdate pool.ntp.org
Synchronize time with ntp server

#sudo vim /etc/default/ntpdate
# Set to "yes" to take the server list from /etc/ntp.conf, from package ntp,
# so you only have to keep it in one place.
NTPDATE_USE_NTP_CONF=no
###ntpdate-debian doesn't use /etc/ntp.conf###

# List of NTP servers to use (Separate multiple servers with spaces.)
# Not used if NTPDATE_USE_NTP_CONF is yes.
NTPSERVERS="0 pool.ntp.org 1 ntp.ubuntu.org"

# Additional options to pass to ntpdate
NTPOPTIONS="-u"
NTPSERVERS = " 10.10.1.20" ### it will override ntpservers setting ###

#sudo hwclock -w
update BIOS time

#sudo hwclock -r
read time from BIOS

#cp /usr/share/zoneinfo/Asia/Taipei /etc/localtime
modify timezone for Taipei with CST