CentOS 6 times, time zone, set modification and time synchronization

One, time zone

Show Time zone

Date--help Get help

Date-r

Date +%z

The above two commands are available

[Root@localhost ~]# date-r; Date +%z
Fri, Oct 23:34:27 +0800
+0800

The main one is the back +0800, East area eight.

Modify Time Zone

Cp/usr/share/zoneinfo/asia/shanghai/etc/localtime

Time zone information exists under/usr/share/zoneinfo/, the local time zone information exists/etc/localtime, using the tab skill, you can modify the time zone arbitrarily

Tzselect, interactive command, but it seems not too good, or use the above bar.

Second, Time

Concept: Linux time has two

System time: Also called software time (SYS), the number of seconds from January 1, 1970 to the current time

Bois time: Also called hardware time (HC)

Show time

[Root@localhost ~]# date;hwclock-r
October 19, 2012 Friday 23:39:44 CST
October 19, 2012 Friday 23:39 45 sec -0.317993 seconds

Set time

1, Date-s

Date-s 20121019

Date-s 23:40:00

You can use this if you don't have a network.

2, Ntpdate

Ntpdate time.windows.com && hwclock-w

Networking update time, if successful, will be system time, written to Bois

Hwclock-w or Hwclock--SYSTOHC

Can do in crontab

3, start the NTPD service, open after 2 can not be used.

Update with Ntpdate to make sure time doesn't vary too much

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.

The knowledge of NTP refer to the server chapter of Brother Bird