Print job not deleting when no output from filter?

[Tim Pushor]

Hello,

We have implemented a fill-out form based printing system for a legacy 
application in which we essentially print a file of key/value pairs 
which a filter script (as defined in convs) fills out fields in a PDF 
file and outputs the filled out PDF.

This has worked very well for us. So well in fact that we decided to 
expand on it and allow the system to also email and fax these forms from 
our application. If we want to print or email a form, we print to a null 
printer (file://dev/null), and the filter script handles dispatching the 
  form off to hylafax or attaches it to an email and sends it off. 
Again, this works very well.

The problem is that in this case, the filter script does not output 
anything, we get a log entry in the CUPS error file:

> E [06/Aug/2010:16:36:33 -0600] [Job 391892] Empty print file!

And the print job does not get deleted. After a while these jobs pile up 
and CUPS will no longer accept jobs.

I'm using cups 1.2.4 (from CentOS / RHEL)

There are ways that I can get around it, but does anyone have any 
suggestions as to how I - from a filter script - can tell the print 
system that I don't actually want to print anything and the print job 
should get deleted?

Thanks,
Tim