笔者安装Ubuntu系统时选择了英文界面，所以导致时区不对。那么怎么将系统时间设置为北京时间，请看下面。
在终端输入sudo tzselect命令，然后根据提示选择Asia->China->Beijing Time
在使用sudo ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime命令强制创建软连接，这时就可以看到系统时间自动更新为北京时间了。
操作日志：
tangjz-ros@ubuntu [09:05:06 PM] [~]
-> % sudo tzselect
[sudo] password for tangjz-ros:
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.
#? 4
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
#? 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.
Selected time is now: Fri Aug 9 20:56:39 CST 2019.
Universal Time is now: Fri Aug 9 12:56:39 UTC 2019.
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
tangjz-ros@ubuntu [09:05:06 PM] [~]
-> % sudo ln -sf /usr/share/zoneinfo/Asia/Shanghai /etc/localtime