CentOS 6th time, 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

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1. [Email protected] ~]# date-r; Date +%z
2. Fri, Oct 2012 23:34:27 +0800
3. +0800

[Email protected] ~]# date-r; Date +%zfri, Oct 2012 23:34:27 +0800+0800

The main is the back of the +0800, East eight district

Modify Time Zone

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

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

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

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1. [Email protected] ~]# Date;hwclock-r
2. Friday, October 19, 2012 23:39:44 CST
3. October 19, 2012 Friday 23:39 45 sec -0.317993 seconds

[[email protected] ~]# date;hwclock-r2012 October 19 Friday 23:39:44 CST2012 year October 19 Friday 23:39 45 seconds -0.317993 seconds

Set the time

1, Date-s

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1. Date-s 20121019

Date-s 20121019

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1. Date-s 23:40:00

Date-s 23:40:00

You can use this without a network.

2, Ntpdate

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1. Ntpdate time.windows.com && hwclock-w

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.

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

CentOS 6th time, time zone, settings modification and time synchronization