Linux time zone settings modification and time synchronization

Linux time zone settings modification and time synchronization
One, time zone
Show Time zone
Date--help Get help
Date-r
Date +%z
All of the above two commands can be
[Email protected] ~]# date-r; Date +%z
Fri, Oct 2012 23:34:27 +0800
+0800
The main is the back of the +0800, East eight district
Modify Time Zone
Cp/etc/localtime/etc/localtime.bak #备份系统默认时区
Cp/usr/share/zoneinfo/asia/shanghai/etc/localtime #设置中国时区
The time zone information exists/usr/share/zoneinfo/below, the local time zone information exists/etc/localtime, using the TAB key technique, can modify the time zone arbitrarily
Tzselect, interactive command, but it seems to be not very good, or use the above bar.
Second, time
Concept: Linux time has two
System time: Also called software time (SYS), January 1, 1970 to the current time of the number of seconds
Bois time: Also called hardware time (HC)
Show time
[Email protected] ~]# Date;hwclock-r
Friday, October 19, 2012 23:39:44 CST
October 19, 2012 Friday 23:39 45 sec -0.317993 seconds
Set the time
1, Date-s
Date-s 20121019
Date-s 23:40:00
You can use this without a network.
2, Ntpdate
Ntpdate time.windows.com && hwclock-w
Network update time, if successful, will system time, write Bois
Hwclock-w or Hwclock--SYSTOHC
Can do crontab.
3, start the NTPD service, opened after 2 can not be used.
Update with Ntpdate first, make sure time is not too different
Rpm-qa | grep NTP #查询一下可安装了
Chkconfig--list | grep NTP #看下服务情况
CHKCONIFG ntpd on
Service ntpd start or/etc/init.d/ntpd start
If necessary, set the/etc/ntp.conf, and then reload the service.

This article is from the "Boyhack" blog, make sure to keep this source http://461205160.blog.51cto.com/274918/1718456

Linux time zone settings modification and time synchronization