How to modify time zone and time in ubuntu system

On a Linux computer, there are two times, one is the hardware time (the time recorded in the BIOS, called hwclock), and the other is the operating system time (osclock). The hardware clock is powered by the BIOS battery,

When the computer is shut down, it will continue to run. The BIOS battery can generally be used for several years. If the battery is dead, the data in the BIOS will be restored to factory settings.

The interaction process between hardware time and operating system time

1、 When booting, the operating system reads the hardware time + time zone from the BIOS, and then converts it to the corresponding time according to the time zone of the osclock. Then the operating system time and the hardware time run independently and do not affect each other. We

The time obtained through the application is all operating system time. This step is done automatically by os when booting.

2、 When the host is running, ntp is used to ensure that osclock is synchronized with the international atomic time, and then osclock is synchronized to hwclock. This step needs to be configured by yourself

3、 When shutting down, osclock writes hwclock. This step is done automatically by os when shutting down. However, we have to consider the abnormal shutdown. When the abnormal shutdown occurs, osclock may not write hwclock. This is why

What is the reason for flashing osclock into hwclock regularly in step 2. If you flash in from time to time, when the gap between osclock and hwclock is large, if you shut down abnormally, osclock will be lost. When you turn it on again, osclock will be

Wrong, when the first ntp synchronization comes, osclock is always wrong. And if ntpd is used, ntpd is gradual adjustment, and osclock is adjusted to international atom after multiple ntp synchronization cycles.

In addition, if the time difference between osclock and ntp server exceeds 1000 seconds, ntp server will not update osclock.

How to modify time zone and time in ubuntu

First check the time zone:

codetc@webubuntu:~$ date -R
Tue,17 Dec 201318:23:01+0800

If you want to modify the time zone, execute sudo tzselect

Select region: Asia

codetc@webubuntu:~$ sudo tzselect
[ sudo] password for codetc: 
Please identify a location so that time zone rules can be set correctly.
Please select a continent or ocean.1) Africa
 2) Americas
 3) Antarctica
 4) Arctic Ocean
 5) Asia
 6) Atlantic Ocean
 7) Australia
 8) Europe
 9) Indian Ocean
10) Pacific Ocean
11) none - I want to specify the time zone using the Posix TZ format.
#?5

Select country: China

Please select a country.1) Afghanistan      18) Israel        35) Palestine
 2) Armenia        19) Japan         36) Philippines
 3) Azerbaijan      20) Jordan        37) Qatar
 4) Bahrain        21) Kazakhstan      38) Russia
 5) Bangladesh      22)Korea(North)39) Saudi Arabia
 6) Bhutan        23)Korea(South)40) Singapore
 7) Brunei        24) Kuwait        41) Sri Lanka
 8) Cambodia       25) Kyrgyzstan      42) Syria
 9) China         26) Laos         43) Taiwan
10) Cyprus        27) Lebanon        44) Tajikistan
11) East Timor      28) Macau         45) Thailand
12) Georgia        29) Malaysia       46) Turkmenistan
13) Hong Kong       30) Mongolia       47) United Arab Emirates
14) India         31)Myanmar(Burma)48) Uzbekistan
15) Indonesia       32) Nepal         49) Vietnam
16) Iran         33) Oman         50) Yemen
17) Iraq         34) Pakistan
#?9

Select time zone: Beijing time

Please select one of the following time zone regions.1) east China - Beijing, Guangdong, Shanghai, etc.2)Heilongjiang(except Mohe), Jilin
3) central China - Sichuan, Yunnan, Guangxi, Shaanxi, Guizhou, etc.4) most of Tibet & Xinjiang
5) west Tibet & Xinjiang
#?1

Confirm verification:

The following information has been given:
 China
 east China - Beijing, Guangdong, Shanghai, etc.
Therefore TZ='Asia/Shanghai' will be used.
Local time is now:   Tue Dec 1718:22:10 CST 2013.
Universal Time is now: Tue Dec 1710:22:10 UTC 2013.
Is the above information OK?1) Yes
2) No
#?1
You can make this change permanent for yourself by appending the line
 TZ='Asia/Shanghai';export TZ
to the file '.profile'in your home directory; then log out and log in again.
Here is that TZ value again,this time on standard output so that you
can use the /usr/bin/tzselect command in shell scripts:
Asia/Shanghai

Copy files to the /etc directory

sudo cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

Update time

sudo ntpdate time.windows.com

After modifying the time, modify the hardware CMOS time

sudo hwclock --systohc

to sum up

The above is the entire content of this article. I hope that the content of this article has a certain reference value for your study or work. Thank you for your support to ZaLou.Cn. If you want to know more about it, please check the related links below