A small family setup...

I have a color printer, and a Linux computer, with CUPS installed. I wan to allow the kids to print, but only in draft mode, and only in greyscale.

With CUPS I prevented the kids' account from accessing the printer. Then I set up a second printer, for the same hardware printer, but with different default options (draft and greyscale), and allowed the kids to access this new printer.

It works, when they print the default options for this new printer are indeed draft and greyscale. But they are just that, default options. They can change it.

Is there a way to prevent users from changing the options of a printer ?

My guess (never done it): when logged into the linux pc, the username used by the kids should not have the permission https://community.kde.org/Printing/CUPS/Access_Control
(all my pcs home has lpadmin group access and I dont have user restrictions; however I would look at the link and try it.. if I were you).

@floppy_stuttgart : no, even non-members of lpadmin can change the print options before printing

Access Control is binary : either a user has access to a printer, or he doesn't. Access Control doesn't permit control what options of a printer a user has access to (no fine grained control).

Without a lot of in depth reading I found this link
https://www.cups.org/doc/policies.html
which may have some of the answers for your issue with cups.

@computersavvy : same answer as given to @floppy_stuttgart. CUPS policies are binary, either you allow access to a print queue, or you don't. No fine grained control there. Thus, it can not be used to enforce specific print options.

For this second printer config, modify the ppd for that config so that only draft and greyscale output is possible (ie strip out the unwanted options).

1 members found this post helpful.

Thanks. Yes that's probably the way to go. I also just fell upon the Tea4CUPS project, which seems to provide a way to override options just before sending the job out to the printer.

https://wiki.debian.org/CUPSTea4CUPS
Homepage : http://www.pykota.com/software/tea4cups

Thanks for sharing those links re Tea4CUPS. Let us know how you get on.

I probably won't test Tea4CUPS. I just tested your idea (modifying the PPD). It's really straightforward and works perfectly, all I had to do is modifying /etc/cups/ppd/myDRAFTprinter.ppd and comment the "*OpenUI *ColorModel/Output Mode: PickOne" and "*OpenUI *OutputMode/Print Quality: PickOne " sections.

It works perfectly !

Only funny thing is, LibreOffice still shows the color and print mode option lists (but gray/draft is enforced, no matter what options the user chooses in LibreOffice). Other applications like Firefox don't show color and output mode dialogs anymore, as expected. I think it's due to the fact that LibreOffice does its own thing to build its print dialogs, it doesn't use GTK's standard print dialog. It's color options and output modes are probably hard-coded somewhere.

Anyway, it works, even with LibreOffice, the printer is now a "gray only draft printer" !

Thanks

Good to read of your success with this. Glad to have been of guidance.