http://www.cnblogs.com/hwaggLee/p/5468029.html
http://man.linuxde.net/ntpdate
http://www.cnblogs.com/13188196we/archive/2012/10/20/ntp.html
http://www.cnblogs.com/hwaggLee/p/5468029.html
http://man.linuxde.net/ntpdate
http://www.cnblogs.com/13188196we/archive/2012/10/20/ntp.html