Time modification under Linux

The Linux system has two time, one is the system time, the other is the CMOS time.

Need to put two time to tune!

Method One: Modify the system time

(1). Log in as root and adjust the system time with the date command

Date-s "2017/11/10 10:20:00" Change the system time to November 10, 17 10:20

This modification fails after the system restarts, so in order to make this time permanent, the modified time needs to be written to the CMOS.

(2) then perform hwclock-w to synchronize the system time to CMOS time

Time to look at CMOS:

#hwclock/clock–r

Writes the current system time to the CMOS

#hwclock/clock–w

Method Two: Modify hardware time

(1). Log in as root and tune CMOS time with hwclock/clock--set--date command

Hwclock/clock--set--date== "10:20:00 2017-11-10" to change CMOS time to November 10, 2017 10:20 0 seconds)

(2) then perform hwclock-s to synchronize CMOS time to system time

0 0 * * hwclock-s can be added under the root user's crontab-e

Keep syncing every day

Common formatting:

A, Hwclock/clock--set--date= "month/day/year: minutes: Seconds"

#hwclock/clock--set--date= "09/17/2003 09:54:00"

b, or hwclock--set--date hh:mm:ss command

Hwclock/clock--set--date 09:54:00

Hwclock: Hardware Clock

-W: Synchronizing system time to hardware time

-S: Synchronizing hardware time to System time

In Linux system, CMOS time is more accurate, but system time error is large (especially virtual machine).

Date-r/etc/passwd//View the last modified time of the file

This article is from "Operation and maintenance record Mei Ling" blog, please be sure to keep this source http://meiling.blog.51cto.com/6220221/1980557

Time modification under Linux