ubuntu 14.04 service networking restart 无法重启

更改了 /etc/network/interfaces

要重启一下网卡，使其生效

使用命令 service networking restart 无法重启，并报错

stop: Job failed while stopping
start: Job is already running: networking


原因：
This was never a supported way to bounce the network, starting with 14.04, we changed the init script to fail rather than possibly trash your machine.

If you look at upstart's log, you'll notice the following message:
Stopping or restarting the networking job is not supported.
Use ifdown & ifup to reconfigure desired interface.


在 14.04 版本中，取消了 service networking restart 的功能，只能使用 ifdown和ifup 来重新配置网卡接口