Development of CUPS backend proxy

[alex at j2anywhere.com]

I am trying to write an print job interceptor. This best seems to be done in a backend rather then a wrapper. From the previous suggestion to chain filters together I though I could do the same with backends. I created a script which forwards all request to the parallel script. My script is called, but the print job is never forwarded to the "real" backend. The error message indicates that the file "/usr/lib/cups/backend/parallel" is busy. Look like either the file or the device "/dev/lp0" are locked.

If this assumption is correct :
-How can I either unlock the file or device or prevent them from being locked in the first place.

-Could is dis-associate my "fake" backend from the device or file to prevent the lock. I have to admit I don't fully understand how the association occurs.

Thanks
Alex