stop vs. cupsdisable

[Kurt Pfeifle]

> Hello all.
>
> I'm a bit confused about the use of reject and cupsdisable. These
> commands are almost identical in functionality except that one deals
> with print jobs and the other, the physical printer itself but both
> affects the print jobs.
>
> Reject:
> When a printer queue is set to reject, my understanding is the printer
> will complete its current print job and subsequent jobs are simply
> discarded and never queued up. When I say complete, I mean if there's
> a 5Mb file being printed and the printer has not yet received all data and in the middle of printing and receiving data from the server, you
> set the printer queue to reject, the printer will continue to
> receive/print until it has completely received all data from the
> server and printed everything for that current job. True or False?

Not correct.

"Reject" switches cupsd into a mode that rejects any new job to enter the queue. (And the user should see a message that his job was rejected...) Previous jobs which are already queued will continued to be processed and printed until the queue is completely empty.


> Cupsdisable:
> When a printer queue is set to disable, the printer will halt its
> current print job, placed the job back in queue, and stop printing
> immediately. Subsequent printjobs will be kept in queue. Whe you start
> the printer again, the printer will start printing from the last job
> before it was stopped. True or False?

Correct.


Maybe a model helps explain it better:

* The printjob queue is a long tube which has to be passed by each job.

* The tube is all in CUPS' realm, and has nothing to do with the physical printer. The physical printer is located behind the tube's exit.

* The tube has two shutters, one on each end.

* Each shutter can be opened or closed independently from the other one.

* If both shutters are open, the jobs get processed normally.

* If the exit shutter is open, all queued jobs get processed until the tube is empty; processing includes being sent off to the physical printer.

* If the entrance shutter is open, new new jobs can enter the tube.

* If the entrance shutter is closed, no new new jobs can enter the tube any longer.

* If the exit shutter is closed, the current jobs stay waiting in the tube (until the shutter opens again, or until they are flushed into the "delete" sink).

* The shutters are operated by users with administrative privileges.

  ==> The entrance shutter is switched into open or closed mode with the "accept" and the "reject" commands.

  ==> The exit shutter is switched into open/closed with "cupsenable"/"cupsdisable".