how to filter to pdf, then pass to custom backend?

[Helge Blischke]

Ted Tanaka wrote:

> Thanks for the reply, Paul.
> 
> I may be getting confused between filter and backend.  Are you suggesting
> I have my custom backend call the CUPS-PDF backend?  I wasn't planning on
> adding a custom filter, just a custom backend.  And for some reason I
> didn't think a backend could call another backend, unless of course I
> someone connect together the signals and stdin/stdout/stderr.
> 
> Thanks!
> 
> 
>> You can call as many filters as you want from your custom filter.  Just
>> pass $1 - $5 and usually you have to fib on $6 since you are stacking
>> filters.  Usually I just use my temp files in $TMPDIR.  Just don't forget
>> to clean up after yourself.  Let me know if you need an example let me
>> know.
>>
>> > Hey everyone -
>> >
>> > Hope you can help me out.  I need to convert print jobs to PDF then
>> > pass them to a custom backend.
>> >
>> > The options seem to be:
>> > - add a pstopdf filter, then call my custom backend
>> > - write something like the pdf2email script that calls ghostscript to
>> > convert to pdf - figure out how to daisy chain backends and use
>> > CUPS-PDF, then chain my custom backend - hack CUPS-PDF to add my custom
>> > functionality.
>> >
>> > I know there's CUPS-PDF, but since there can be only a single backend,
>> > I can't add my own custom backend.
>> >
>> > I noticed a pstopdf filter, but when I added it to mime.conv, I get the
>> > error:
>> >
>> >  client-error-document-format-not-supported: Unsupported format
>> >  'application/postscript'
>> >
>> > Any suggestions on the best way to do this?
>> >
>> > Thanks!
>>

Perhaps you may have a look at the prtofile backend (see the links on the 
CUPS website). It offers to execute a Perl fragment for postprocessing.

Helge