问题描述：有些CentOS 7.7系统配置完ntp后，时间同步正常；通过data查看本地时间，发现时间比正常时间少8个小时。
一、主机环境：
1、系统版本：

root@xuhs:/root>cat /etc/redhat-release 
CentOS Linux release 7.7.1908 (Core)

2、查看ntp同步情况如下：
（1）查看客户端本地时间：

root@xuhs:/etc>date
Thu May  6 09:51:44 UTC 2021

（2）查看与ntp服务端的时间同步情况：

root@xuhs:/root>ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*192.168.100.11  LOCAL(1)         6 u  104  128  377    0.303   47.369   8.419
root@xuhs:/root>

（3）查看当前主机链接时区的情况，显示如下：

root@xuhs:/etc>ls -ltr /etc/loca*
lrwxrwxrwx. 1 root root  35 May  6  2021 /etc/localtime -> ../usr/share/zoneinfo/UTC

二、修改时区设置:
1、修改方法：修改时区为北京时区，操作如下：

root@xuhs:/etc>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) Beijing Time
2) Xinjiang Time
#? 1

The following information has been given:

        China
        Beijing Time

Therefore TZ='Asia/Shanghai' will be used.
Local time is now:      Tue May 6 17:56:42 CST 2021.
Universal Time is now:  Tue May 6 09:56:42 UTC 2021.
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

2、修改localtime：
（1）备份：
root@xuhs:/etc>mv localtime localtime.bak
（2）重新进行链接到时区文件：

root@xuhs:/etc>ls -ltr /etc/loca*
lrwxrwxrwx. 1 root root  35 May  6  2021 /etc/localtime -> ../usr/share/zoneinfo/Asia/Shanghai
root@xuhs:/etc>date
Tue May 6 17:58:22 CST 2021

3、显示时间正常即可；

root@xuhs:/etc>ls -ltr /etc/loca*
lrwxrwxrwx. 1 root root  35 May  6  2021 /etc/localtime -> ../usr/share/zoneinfo/Asia/Shanghai
root@xuhs:/etc>date
Tue May 6 17:58:22 CST 2021