I need to insert a filter into a normal print stream.

[Kurt Pfeifle]

> One of my clients is trying to handle electronic journaling of their printers. Instead of having to use three layer paper they want to have the information sent to the printer to be duplicated to a file and then possibly processed.
>
> They are basically printing invoices to a Lanier printer and they want to have the text they are sending processed and saved to disc for archiving.
>
> I know CUPS has filter chains but I haven't found a way to say "ok, the input you get send it to this filter and then take the output of that filter and send it on it's merry way".
>
> So how would you be able to insert a filter in the path of the data stream? The lanier ppd is using foomatic but I still haven't found a way to slip something in the way.
>
> Any help or outlandish suggestions would be appreciated.


Have a look here:

    http://techbase.kde.org/Projects/KDEPrint/Tools%2BUtilities

and try to grok what the "2file" and "2dir" CUPS backend scripts are doing. (CUPS "filters" basically work the same way. A CUPS "backend" is just a special filters, the last one in the chain that is passed by the job data before it goes to the real print device.)