Mac Geekery

CUPS is the name of the service that handles printing in Mac OS X 10.3 to 10.5. It has a lot of features that aren’t really pushed in the GUI in Mac OS X, but users are able to get at those features by using the special administrative interface at http://localhost:631/.

One of those features is classes. A class, in this context, is a group of printers that can be made to look as if it were one printer. This is great in lab settings where you have half a dozen printers of the same type as you can add them all to a class on a print server and have everyone print to that queue. Then whichever printer is free (or round-robin) will print the job.

This works for mobile users quite well because of that last bit. If a printer is unavailable then it will move to one that is. So if you have a printer at home and a printer at work, then you can make a class of them and the system will print to whichever is currently available.

If you have multiple printers at a location and you add them to a class, expect to run around a lot. This works best when the printers are either side-by-side or mutually unavailable. Adding all the printers within walking distance will suck pretty badly because there’s no notification as to which printer took the job other than the momentary printer queue in the Dock.

Ensure that all the printers you want to use are added to your system and then go to the CUPS management interface. Go to administration and then to add class. Select the printers to use and then give the queue a name. When you click on “Add Class” you’ll need to give the system the login information for an admin user on your local machine (which should not be you).

Now go to print in any program and this new printer should be available. Use it and the job will be delivered to the currently-available printer.

You may be tempted to put a PDF printer in the mix as a backup printer. This won’t work because it’s always available and the class will do things round-robin. Some jobs will be printed and some will be PDFs.