Ubuntu 矫正系统时间

最近在将操作系统习惯转为Ubuntu，发现系统时间不正确，时区是美国而不是中国，这里需要矫正一下。

1、安装ntpdate，同步标准时间

    $ sudo apt install ntpdate

2、修改时区

ubuntu@ubuntu:~# tzselect
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) Arctic Ocean
 5) Asia
 6) Atlantic Ocean
 7) Australia
 8) Europe
 9) Indian Ocean
10) Pacific Ocean
11) coord - I want to use geographical coordinates.
12) TZ - I want to specify the time zone using the Posix TZ format.
#? 5
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.
Local time is now:    Thu May 30 10:09:37 CST 2019.
Universal Time is now:    Thu May 30 02:09:37 UTC 2019.
Is the above information OK?
1) Yes
2) No
#? yes
Please enter a number in range.
#? 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

3、保存时区文件

$ cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime

4、保存到系统底层

    $ hwclock --systohc

5、重启系统

    $ reboot

重启完成后，查看系统时间，如图所示：

ubuntu系统时间矫正成功。