upstart replace sysvinit

初稿于20060923
由于linux系统起动的日益复杂，开发人员一直在寻找一种代替init的东西，今天，Scott James在planet debian上已经证实了upstart可以投入到universe中了，upstart是基于事件驱动的，大体上分为三大类：
“startup”, on system boot.
“shutdown”, when the system is about to be shut down.
“stalled”, when there are no jobs running and no events in the queue.

然后在每一个类别中可以定义其他的事件,比如shutdown中：

“reboot”,
“halt”,
“poweroff”,
“maintenance” (aka. going into “single user” mode),
any user-defined event with shutdown -e event.
from:

http://blog.netsplit.com/articles/2006/09/01/upstart-can-now-replace-sysvinit