Bug#398278: closed by Guus Sliepen (Re: ifupdown: return errors, help me turn off sit0)

[積丹尼 Dan Jacobson]

OK. Maybe the man page should note that it never returns an error
# ifdown $RANDOM; echo $?
ifdown: interface 25627 not configured
0
~# ifup $RANDOM; echo $?
Ignoring unknown interface 19105=19105.
0
so one cannot use $? to test for success.