ubuntu16 运行命令dpkg-reconfigure tzdata,选择Asia–>Shanghai,确定，

ubuntu12:

1.首先查看时区：

swfsadmin@swfsubuntu:~$ date -R
Tue, 17 Dec 2013 18:23:01 +0800

如果要修改时区，执行sudo tzselect

2.选择区域：亚洲

swfsadmin@swfsubuntu:~$ sudo tzselect
[sudo] password for swfsadmin: 
Sorry, try again.
[sudo] password for swfsadmin: 
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

3.选择国家：中国

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

4.选择时区：北京时间

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

5.确认验证：

The following information has been given:

        China
        east China - Beijing, Guangdong, Shanghai, etc.

Therefore TZ='Asia/Shanghai' will be used.
Local time is now:      Tue Dec 17 18:22:10 CST 2013.
Universal Time is now:  Tue Dec 17 10:22:10 UTC 2013.
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

6.复制文件到/etc目录下

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

7.更新时间

sudo ntpdate time.windows.com

改时间参考：

修改时间

sudo date -s MM/DD/YY //修改日期
sudo date -s hh:mm:ss //修改时间

在修改时间以后，修改硬件CMOS的时间

sudo hwclock --systohc //非常重要，如果没有这一步的话，后面时间还是不准