Systemd - http://www.ibm.com/developerworks/cn/linux/1407_liuming_init3/index.html
UpStart - http://www.ibm.com/developerworks/cn/linux/1407_liuming_init2/index.html
sysvinit - http://www.ibm.com/developerworks/cn/linux/1407_liuming_init1/index.html
原文：http://my.oschina.net/meilihao/blog/355551