How does the Linux system view the time zone where the settings are located? __linux

Reproduced from:
https://blog.csdn.net/huangjin0507/article/details/46368623

Second, how the Linux system to see the settings in the time zone.

Method 1: Use the date command to view the time zone

[Root@db-server ~]# Date-r

Sun, 2015 07:10:28-0800.

As shown in the RFC 2822 format, the above command outputs-0800 for the West VIII region, which is the time zone of San Francisco, and below represents the East eight region of our country (+0800)

[ROOT@LNX01 ~]# Date-r

Sun, 2015 23:06:02 +0800

Method 2: View the clock system configuration file

[Root@db-server ~]# More/etc/sysconfig/clock
Zone= "America/los_angeles"
Utc=true
Arc=false
As shown above, indicates that the time zone set by the system is "America/los_angeles", which is the West eight area.

How does the Linux system set up the time zone in which the system is located?

Method 1: There are many time zone files under/usr/share/zoneinfo/that can replicate these time zone files to overwrite/etc/localtime files:
[Root@db-server ~]# Date-r
Mon, 2015 10:42:26 +0800
[Root@db-server ~]# Cp/usr/share/zoneinfo/asia/shanghai/etc/localtime
Cp:overwrite '/etc/localtime '? Y
[Root@db-server ~]# Date-r
Sun, 2015 18:42:49-0800.
[Root@db-server ~]#

Mode 2: Modify the time zone file for the link/etc/locatime:
[Root@db-server ~]# Ln/usr/share/zoneinfo/asia/shanghai/etc/localtime

Ln:creating hard Link/etc/localtime ' To/usr/share/zoneinfo/asia/shanghai ': File exists

[Root@db-server ~]# Rm/etc/localtime

Rm:remove regular file '/etc/localtime '? Y

[Root@db-server ~]# Ln-sf/usr/share/zoneinfo/asia/shanghai/etc/localtime

[Root@db-server ~]# Date-r

Mon, 2015 10:56:10 +0800

Method 3: Use Tzselect to set the time zone

example, set the system time zone to East area eight (Beijing time)

[root@db-server ~]# tzselect
Please identify a location so this time zone the 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) Austra Lia
8) Europe
9) Indian Ocean
Ten) Pacific Ocean
One) none-i want to specify the time zone using the P Osix TZ format. ? 5

Please select a country.
1) Afghanistan Israel) Palestine
2) Armenia) Philippines
3) Azerbaijan) Q ATAR
4) Bahrain) Kazakhstan Russia
5 Bangladesh) Korea (north)-Saudi Arabia
6) Bhutan) Ko Rea (South) Singapore
7) Brunei Kuwait) Sri Lanka
8) Cambodia Kyrgyzstan) Syria
9) (a) Laos) Taiwan (Cyprus) Lebanon) Tajikistan
(Timor) Macau
) Thailand Malaysia) Turkmenistan
Kong) Mongolia United Arab
-Emirates (India) (a) Uzbekistan
) Indonesia) Nepal Vietnam
Iran) Oman Yemen) Iraq (MB) (PDF) ng>? 9

Please select one of the following time zone regions.
1 East China-beijing, Guangdong, Shanghai, etc.
2) Heilongjiang (except Mohe), Jilin
3) China-sichuan, Yunnan, Guangxi, Shaanxi, Guizhou, etc.
4) Most of Tibet & Xinjiang
5 West Tibet & Xinjiang 1

The following information has been given:

    East
    China-beijing, Guangdong, Shanghai, etc.

Therefore tz= ' Asia/shanghai ' would be used.
The local time is Now:sun a 23:31:51 CST 2015.
Universal Time is Now:sun 15:31:51 UTC 2015.
is the above information OK?
1) Yes
2) No Yes

Please enter 1 for Yes, or 2 for No. ? 1

You can make this change permanent for yourself by appending
tz= ' Asia/shanghai '; Export TZ
To the file '. Profiles ' in your home directory; Then log out and log in again.

Here's that TZ value again, this time on standard output so
can use The/usr/bin/tzselect command in shell scripts:
Asia/shanghai
Note: The Tzselect command only tells you what time zone is selected and does not take effect. So now it's not East 8 Beijing time. You can set the correct TZ environment variables and export them in. Profile,. Bash_profile, or/etc/profile. For example, in. Bash_profile set tz= ' Asia/shanghai '; Export TZ and make it effective.

[Root@db-server ~]# Source Bash_profile

[Root@db-server ~]# Date

Sun 23:37:40 CST 2015

[root@db-server ~]# date-r
Mon, a +0800-up 2015 10:42:26
[root@db-server ~]# cp/usr/share/zoneinfo/americ A/los_angeles/etc/localtime
Cp:overwrite/etc/localtime ' y
[root@db-server ~]# date-r
Sun, 2015 18:42:49-0800
[Root@db-server ~]#
[root@db-server ~]# date-r
Mon, out of 2015 10:42:26 +0800
[root@d B-server ~]# cp/usr/share/zoneinfo/america/los_angeles/etc/localtime
cp:overwrite/etc/localtime ' y
[ Root@db-server ~]# date-r
Sun, 2015 18:42:49-0800
[root@db-server ~]#