Centos系统修改时区
今天在操作系统的时候创建了一个文件，ls了一下发现时间和本地时间不对，date看了一下后发现时区是EDT(Eastern Daylight Timing)指美国东部夏令时间)。时区这玩意，百年难得修改一次，几乎算是最不常用的操作了(除了运维NTP服务器的大神们)，记录一下。

[[email protected] ~]# date
Mon Mar 27 01:26:48 EDT 2017

一、设置Centos系统的时区

输入命令： tzselect
依次输入：5)Asia → 9)china → 1)east China —BeiJing.... → 1)Yes

[[email protected] ~]# 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) 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:	Mon Mar 27 11:38:02 CST 2017.
Universal Time is now:	Mon Mar 27 03:38:02 UTC 2017.
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

二、替换Centos系统时区文件

[[email protected] ~]# date
Sun Mar 26 23:38:13 EDT 2017
[[email protected] ~]#  cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime    #设置中国时区的时间就选择Asia/Shanghai
cp: overwrite ‘/etc/localtime’? yes

三、查看设置后Centos系统时间

[[email protected] ~]# date
Mon Mar 27 11:38:43 CST 2017