Printing to a program doesn't work.

[Luiz Losekann]

I have a BIG problem - I'm looking for a  for a tool in Linux which would be able to print a file to a program which reads from stdin, e.g., like a generic pipe, similar to RedMon in Windows. I found in internet a description how to install a shell script as a CUPS backend. I wrote a shell and move it to CUPS backend - /usr/lib/cups/backend/ -as SU. I had no problems to install it with admin command - checked with lpstat -p or http://localhost:631/printers it is showed as enable and idle printer. But when I sent data using lpr, the "printer" stopped for unknowed reason and return the following message on error_log "PID xxx stopped with status 22". Of course I test the shell script out of CUPS and it works ok. Please, I would like to have a help to tell me if I need to change some configuration item on cupsd.conf or another configuration file.
Thanks in advance.