backend user

[Rubinas]

Hi,

I have question regarding backend(pdf) script. I am using network printer.
First argument which gets scripts is user name. If none authentication is set for a printer when I get computer user name. If authentication is set then I get cups user.

Question: How should I get computer user name using printer with authentication.

I know, that is possible, because printers "Show completed jobs" shows that job with computer user name.