Every once in a while I will get a call that a printer is not working. Users are sending print jobs, but nothing is coming out of the machine. Now, being better grounded in Windows, if it is one of our normal networked printers, I can easily fix it. If it is one of the linux printers, however, it is a much different story. Luckily, linux (and CUPS) has some awesome built in assistance.
CUPS Web Access: Your printers can be viewed in a GUI webapp that comes by default with CUPS. You can access it my visiting http://localhost:631. This allows you to enable/disable printers, modify print queues, and view print jobs.
lpstat and cancel commands: I am a little more fuzzy on these commands, but I can stumble around getting them to work for me. lpstat, which no switches, will list the print jobs currently being processed. The output is in the format of printerName-jobNumber. This is where the cancel command comes in. If a print job is stuck in the queue, and for whatever reason will not process, you can manually remove it with the cancel command.