More simple syntax questions

Hello mighty procmail masters,


1) What is a simple way to use $? to set a variable if it is not already 
defined?

I've tried using recipes, and simple equates like

   # Set $VAR if not already set
   VAR=`if !($?VAR) echo "value"`

but, obviously, that will clear VAR if already set.

Also, what is the syntax for a condition?

   #deliver to "bad" folder if $VAR undefined
   :0:
   * $VAR ?? .....
   bad




2) Is there an cleaner way of doing OR?

  # Do something if file.1 OR file.2 doesn't exist
  :0i
  * ? test -f file.1
  * ? test -f file.2
  {
  }

  :0E
  | (task to do if either file is missing)



3) Just to clear up my old memories:

What is the difference between "w" and "W" flags?  I try both in 
recipes where filter program fail, and I don't see any difference 
in the log file.  I get 'Program failure' messages in both cases.

Also, in a filter I don't need to use the "w" flag if I'm not worried 
about a program failure, correct?

Thanks for the help,

Bill Moseley
moseley(_at_)netcom(_dot_)com