First, the time zone
date -R; date ; hwclock --show ; ps -ef|grep ntpd
The time zone
date --help to get help
date -R
date +%z
These two commands are available
date -R; date +%z
Mainly behind +0800 East eight districts
Change the time zone
cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
Presence information time zone / usr / share / zoneinfo / below, time zone information is present in the machine / etc / localtime
Second, the time
The concept: Linux has two time
System Time: software, also known as time (sys), 1970 Nian 1 January 1 to the current second time
BOIS time: also called hardware time (hc)
display time
date;hwclock -r
October 19, 2012 Friday 23:39:44 CST
October 19, 2012 Friday 23:39:45 -0.317993 seconds
Setting time
date -s 20121019
date -s 23:40:00
Under no circumstances can use this network
2、ntpdate
ntpdate time.windows.com && hwclock -w
Internet update, if successful, the system time, write BOIS
# Synchronize system time to hardware time
hwclock -w or hwclock --systohc [sys system time, tohc hardware time]
# Hardware time synchronized to the system time
clock -hctosys or hwclock --hctosys [hc represent hardware time, sys represents the system time]
You can do the crontab
3, start the ntpd service, it can not be used after the open.
Ntpdate first with updates to make sure that time will not differ too much
rpm -qa | grep ntp # check what can be installed
chkconfig --list | grep ntp # facie case of service
chkconifg ntpd on
service ntpd start 或/etc/init.d/ntpd start
If necessary, set about /etc/ntp.conf, then service reload it.