ifup和ifdown

unigium

/sbin/ifup和/sbin/ifdown这两个命令
1、是在什么时候运行的？
2、为什么需要这两个命令，有/etc/rc.d/init.d/network不就可以了么？
3、这两个命令具体应该怎么用？
谢谢大家的指导

ThinkPad_

ifup/ifdown
For each installed network adapter, there is a corresponding ifcfg-* file in
/etc/sysconfig/network-scripts. You can activate or deactivate that adapter with
the ifup and ifdown commands. Either one of the following commands will activate
the eth0 network adapter:
ifup ifcfg-eth0
ifup eth0