What command to use inside /etc/network/interfaces to take an interface down

[Jaime]

Hi all.

I'd like to use a command inside my /etc/network/interfaces to
automatically take down the eth0 interface before I "ifup" another
interface called rausb0. I realize the place to put it is inside the
"iface rausb0" stanza, and it should listed after the "pre-up" command
option.

If I use "pre-up ifdown eth0", then ifuping rausb0 just hangs (I think
this is related to
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=231197 but I'm not
sure.

If I use "pre-up ip link set dev eth0 down", then the eth0 is indeed
taken down ("ip link" shows me it is down), but the file
"/etc/network/ifstate" is not updated - this file thinks that eth0 is
still up.

Does anyone know the correct command to use?

Many thanks,

Jaime