设定Linux时区

Local vs. UTC
首先重要的问题是你使用utc还是local time.
UTC(Universal Time Coordinated)=GMT(Greenwich Mean Time)
Local time 是你手表上的时间

传统的POSIX计算机(Solaris,bsd,unix)使用UTC格式
linux可以处理UTC时间和蹩脚的Windows所使用的local time

到底是使用UTC还是local time可以这样来确定：
如果机器上同时安装有Linux和Windows，建议使用local time
如果机器上只安装有Linux，建议使用utc
确定后编辑/etc/sysconfig/clock, UTC=0 是local time; UTC=1 是UTC(GMT)
确定timezone
运行tzselect,回答问题后会告诉你时区的名称，比如"Asia/Shanghai",把他记下来(后面我用$timezone代替)
设定timezone
# cp /usr/share/zoneinfo/$timezone /etc/localtime
重新启动或者运行时钟设置脚本使之发生作用
版本差异
由于发行版的差异，以上文件位置可能不同。
一般设置时钟所使用的启动脚本为/etc/rc.d/init.d/setclock
redhat是在/etc/rc.d/rc.sysinit中设置时钟，所以一般要重新启动

运行tzselect命令之后的提示：
[root@saggcc ~]# date
Fri Jul  9 10:08:44 EDT 2010
[root@saggcc ~]# hwclock -r
Fri 09 Jul 2010 10:08:50 AM EDT  -0.320560 seconds
[root@saggcc ~]# cd /etc/
[root@saggcc etc]# cd localtime
-bash: cd: localtime: Not a directory
[root@saggcc 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) 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

The following information has been given:

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

Therefore TZ='Asia/Shanghai' will be used.
Local time is now:      Fri Jul  9 22:10:20 CST 2010.
Universal Time is now:  Fri Jul  9 14:10:20 UTC 2010.
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