How to start an interface from command line?

How can a command line user or script initiate an interface restart, for example, to bring up or shut down the ‘wan’ or ‘wan6’ interface?

ifconfig interface_name up/down

ifconfig is for low-level interface names, it doesn’t work with the interfaces defined in OpenWRT:

# ifconfig wan down
ifconfig: SIOCGIFFLAGS: No such device

to put it another way, what is the command that LUCI invokes when somebody clicks the “Connect” button next to an interface?

ok i was wrong sorry…

ifup interace_name
ifdown interface_name

tested working…