修改centos8时间格式为24小时制

1.使用tzselect命令

[root@localhost ~]# tzselect

请确定一个位置，以便正确设置时区规则。
请选择大洲、海洋、“coord”或“TZ”。(“目标位置”或“时区”)

Please identify a location so that time zone rules can be set correctly.
Please select a continent, ocean, "coord", or "TZ".
 1) Africa
 2) Americas
 3) Antarctica
 4) Asia
 5) Atlantic Ocean
 6) Australia
 7) Europe
 8) Indian Ocean
 9) Pacific Ocean
10) coord - I want to use geographical coordinates.
11) TZ - I want to specify the time zone using the Posix TZ format.

选择亚洲，输入4

#? 4

请选择一个与你们国家时钟一致的国家。

Please select a country whose clocks agree with yours.
 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

选择中国，输入9

#? 9

请选择以下时区之一。

Please select one of the following time zone regions.
1) Beijing Time
2) Xinjiang Time

选择北京时间，输入1

#? 1

The following information has been given:

        China
        Beijing Time

Therefore TZ='Asia/Shanghai' will be used.
Selected time is now:   Wed Jul 21 23:29:51 CST 2021.
Universal Time is now:  Wed Jul 21 15:29:51 UTC 2021.
Is the above information OK?
1) Yes
2) No

选择yes，输入1

#? 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. 删除 localtime

[root@localhost ~]# rm /etc/localtime

3. 创建软连接

[root@localhost ~]# ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

4. 验证结果

使用 date 命令查看已设置成功

[root@localhost etc]# date
Mon Aug 19 17:19:00 CST 2019