linux 更换时区

[root@db-server ~]# tzselect 
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
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
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
 
The following information has been given:
 
        China
        east China - Beijing, Guangdong, Shanghai, etc.
 
Therefore TZ='Asia/Shanghai' will be used.
Local time is now:      Sun Jan 11 23:31:51 CST 2015.
Universal Time is now:  Sun Jan 11 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 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

LocalDateTime vs ZonedDateTime输出

这里使用了java 11，java代码当脚本使用，很舒服啊

import java.time.LocalDateTime;
import java.time.ZonedDateTime;

public class DateTest{
        public static final void main(String[] args){
                System.out.println("ZonedDateTime.now(): " + ZonedDateTime.now());
                System.out.println("LocalDateTime.now(): " + LocalDateTime.now());
        }
}

更换了时区，比较两者的输出

[centos@ip-172-26-8-64 ~]$ java DateTest.java
ZonedDateTime.now(): 2018-11-05T12:58:01.013684+08:00[Asia/Shanghai]
LocalDateTime.now(): 2018-11-05T12:58:01.044837
[root@ip-172-26-8-64 centos]$ java DateTest.java
ZonedDateTime.now(): 2018-11-04T23:06:49.888633-06:00[America/Mexico_City]
LocalDateTime.now(): 2018-11-04T23:06:49.918648

ZonedDateTime与LocalDateTime都会去读取当前系统设置的时区，只不过ZonedDateTime多了一个时区的概念