I have created for our customers (no experienced computer users) a
backup utility, which can be scheduled at a specific time.

I am not using gbak.exe directly. Instead I am using the api (calling
sevice_start to start the backup and calling service_query to get a
line of output from the backup thread).

When no error occurs, everything works fine. When some error occurs
(i.e. disk is full) I don't get a return code or error message from
service_query. So the backup just stops, IB server deletes the
incomplete backup file and my application can't distinguish between
success and failure.

Can anyone help me?

Thanks in advance, CL