Verifying user/passwd from shell script?

I have to write a couple of shell scripts (ksh mainly) that call Oracle sqlplus. User/passwd-information for connection to Oracle is passed as a command line option. When I call sqlplus with invalid connection information, I get a prompt for a correct user/passwd combination. This, however, is entirely useless when my script runs in the background or if output goes to /dev/null or something similar. All the user sees is that [Quoted] nothing happens (slooow database today... :-( )

Is there any way that I can find out from a shell script whether a given user/passwd combination is valid or not without hanging on an sqlplus prompt?

Thanks very much,

Martin

PS I speak for myself, not for my company.

-- 
Dr. Martin Ameskamp, AED Graphics AG
Mallwitzstr. 1-3, 53177 Bonn
Tel. 0228/9542-0, Fax 0228/9542-111
Email: ameskamp_at_aed-graphics.de