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CUPS Is ``All Hat and No Cattle'' #6139

Open redmouih opened 9 months ago

redmouih commented 9 months ago

I am running CUPS 2.3.1 on a Dell Precision 7400 running Ubuntu 20.04 (Focal Fossa), driving an EPSON XP7100 connected via WiFi. The printer has been connected via the Ubuntu Settings/Printers page, the CUPS Administration/Printers page, and via command-line lpadmin command. The various displays show the printer as connected to localhost,'' and the printer works--the Epson Printer Utility successfully prints nozzle tests on it. However, it appears that the CUPS software is a pretty front end which produces job queues, but the functionality of putting ink on paper is missing. All print jobs hang, with the messageUnable to locate .local.'' The CUPS debugger returns the error messages Scheduler Not Running'' (although cupsd is running), andThere is no solution to this problem.''

So what's the missing trick? (There is ALWAYS a missing trick. In the entire history of computer science, there has only ever been one software package which actually does what its documentation says it does, and CUPS isn't it.) Specifically, 1) How do I force the computer to convert the printer from connected'' tolocated,'' and 2) how do I force CUPS to transmit a job from a job queue to the physical printer? (I should add that CUPS occasionally puts messages like ``Printing on on the screen, but the physical printer does nothing at all.) Thank you in advance for your advice, colleagues. IHR

debiantriage commented 9 months ago

You have two avenues to explore:

redmouih commented 9 months ago

4 August 2023

Dear Mr. Potkin,

Thank you for taking the time to consider the Issue I posted. The document to which you direct me suggests that I certainly did post to the right venue, as it appears to offer a work-around to my ongoing CUPS problem. The document also answers your second point, as it does list the XP-7100 as AirPrint compatible. Obviously I've got a lot more work to do on this. But many thanks again for your helpful suggestions.

Sincerely, Ian H. Redmount

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debiantriage commented 9 months ago

Give the outputs of

avahi-browse -rt _ipp._tcp
avahi-browse -rt _uscan._tcp
driverless
redmouih commented 9 months ago

Thanks for the response. Here are the outputs you request:

browse01.txt browse02.txt browse03.txt

in order. What do these tell us?

As it happens, CUPS will print its queues properly after it crashes and reboots. (Exactly what crashes and reboots I'm not sure.) The timescale for this is days, not minutes or hours. So is there a command by which I can force CUPS to find its printers?

Thanks again. IHR

debiantriage commented 9 months ago

The content of the three files tell us that the EPSON XP-710o is capable of driverless printing and scanning. Furthermore, it indicates a queue setup with

lpadmin -p xp7100 -v "ipp://EPSON%20XP-7100%20Series._ipp._tcp.local/" -E -m everywhere

should lead to printing taking place wiith


lp -d xp7100 /etc/nsswitch.conf
redmouih commented 9 months ago

No joy. The given lpadmin command returns the response

lpadmin: Unable to connect to "EPSONB78BD4.local:631": Name or service not known

The system shows the indicated printer as connected to localhost. With the localhost:631 server gone, it is difficult to see what is going on.

I might point out that of the 111 open issues here, scores report problems like mine: printers the software can't locate, job queues which hang, CUPS which only runs after a reboot, etc. This suggests a flaw in the software, rather than a user error.