[plug] return values

[Craig Ringer]

> do_something_which_returns_status
> case $? in

oooooooh...
$?

Its amazing what you don't learn in 2yrs of using this darn os.
OTOH that's largely because I've never needed retvals but that's because 
I've been too slack to check them (say, from perl-based filters, the 
most obvious one that could use this calls antiword for .doc while 
updating our story database at work)