I'm interacting programmatically with au (with Perl's Expect module)
and pdbtool (with plain command-lines) and I'm finding that they don't
return useful error codes.  pdbtool returns success, for instance,
after spewing a 'user not found' error on a delete command.  Au
returns success even when it gets an AUTH_FAILURE.

Note, au also does say AUTH_FAILURE on a nu if the user already
exists - should report that the user already exists.

Hope this feedback is helpful.  Now, a question: what's the difference
between au's and pdbtool's 'delete user' functions?  Why must I use nu
to 'create a user' after I've already used pdbtool to create the user?
Very curious.

Randy