linux system clock has two, one is the hardware clock, BIOS that is time that we see a time when the CMOS settings, and a system clock, the system is linux Kernel time. When Linux boots, the system will go read the Kernel hardware clock is set, then the system clock will operate independent of the hardware. Sometimes we find that the system clock and the hardware clock is inconsistent, and therefore need to perform time synchronization, the following will share time setting and clock synchronization and usage instructions.
1, the system time to view and set
Check the system time date
Set the system date:
date command to set the date to June 10, 2019
---- date -s 06/10/19
Set the system time
Set the time 14:20:50
---- date -s 14:20:50
Set the time at 14:16:30 on June 18 2019 (MMDDhhmmYYYY.ss)
----date 0618191614.30
2, view and set the hardware time
View the system hardware clock
hwclock --show or
clock --show
Set hardware time
hwclock --set --date = "06/18/14 14:55" (month / day / year hours: minutes: seconds) or # clock --set --date = "06/18/14 14:55" (month / day / year hours: minutes: seconds)
3, clock synchronization system and hardware.
Hardware clock and system clock synchronization:
# Hwclock --hctosys or # clock --hctosys hc represent hardware time, sys represents the system time, i.e., hardware clock synchronization with the system clock
System clock and the hardware clock synchronization:
# Hwclock --systohc or # clock --systohc i.e. hardware clock synchronized with the system clock