1、 system time
date: Check the current system time
2、 Hardware time
hwclock --show: Check the current hardware time
3、ntpdate
Set the network time to the current system time
1) Installation tools :yum -y install ntp ntpdate
2) Set system time and network time synchronization :ntpdate cn.pool.ntp.org
3) Write system time to hardware time :hwclock --systohc
notes : Close test available