Unable to open device file "/dev/lpt0": Permission denied

Christian Zachariasen chrizach at gmail.com
Wed Apr 23 05:46:48 UTC 2008


On Wed, Apr 23, 2008 at 4:53 AM, David Reedy Jr <davidrjr at comcast.net>
wrote:

> On Tuesday 22 April 2008 10:40:25 am Roland Smith wrote:
> > On Tue, Apr 22, 2008 at 10:08:37AM -0500, David Reedy Jr wrote:
> > > > IICR, the print device should belong to the cups group. At least,
> > > > that's my working setup.
> > > >
> > > > I have the following in /etc/devfs.conf:
> > > >
> > > > # Give cups printer access
> > > > own     lpt0    root:cups
> > > > perm    lpt0    0660
> > >
> > > Thanks for the info. This didn't actually fix the problem, but I
> > > know it was needed since I read somewhere that everything that
> > > cupsd spawns runs as cups.
> > >
> > > What I ended up doing was resetting my cupsd.conf to default and
> > > redid my settings. I must have had a typo in there somewhere before
> > > because as soon as I restarted cupsd after making the changes, the
> > > parallel and usb ports suddenly became available as devices for the
> > > printer.
> >
> > It happens. :-)
> >
> > > I had previously selected lpd and then manually specified the uri
> > > as parallel:/dev/lpt0.
> > >
> > > The laser on the parallel port is now working fine.
> >
> > Good.
> >
> > > I also went ahead
> > > and setup my deskjet on usb:/dev/ulpt0. Print test pages get marked
> > > as completed but nothing actually comes out of the printer. Still
> > > trying to figure that one out.
> >
> > Have a look at the cups logfiles in /var/log/cups. They should give
> > you some pointers. You'll probably need to set the device permissions
> > for ulpt in devfs.rules, not devfs.conf!
> >
> I got the rules setup in devfs.rules, no problem. When I turn on the
> printer it's detected...
>
> ulpt0: <HP Deskjet 3840, class 0/0, rev 2.00/1.00, addr 2> on uhub0
> ulpt0: using bi-directional mode
>
> and things get set right permission-wise...
>
> crw-rw----  1 root  cups        0,  88 Apr 22 21:20 /dev/ulpt0
>
> according to /var/log/cups/error_log it prints...
>
> I [22/Apr/2008:21:20:03 -0500]
> Started "/usr/local/libexec/cups/cgi-bin/printers.cgi" (pid=756)
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Adding start banner page "none".
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Adding job file of type
> application/postscript.
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Adding end banner page "none".
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Queued on "inkjet" by "root".
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Started
> filter /usr/local/libexec/cups/filter/pstops (PID 757)
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Started
> filter /usr/local/libexec/cups/filter/pstoraster (PID 758)
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Started
> filter /usr/local/libexec/cups/filter/rastertohp (PID 759)
> I [22/Apr/2008:21:20:03 -0500] [Job 47] Started
> backend /usr/local/libexec/cups/backend/usb (PID 760)
> I [22/Apr/2008:21:20:06 -0500]
> Started "/usr/local/libexec/cups/cgi-bin/printers.cgi" (pid=761)
> I [22/Apr/2008:21:20:06 -0500] [Job 47] Completed successfully.
> I [22/Apr/2008:21:20:17 -0500]
> Started "/usr/local/libexec/cups/cgi-bin/printers.cgi" (pid=762)
>
> but the job disappears into some sort of black hole. Nothing prints.
> Printer just sits there peacefully doing nothing.
>
> From printers.conf for this printer...
>
> <Printer inkjet>
> Info HP DeskJet 3845
> Location Bottom
> DeviceURI usb:/dev/ulpt0
> State Idle
> StateTime 1208917161
> Accepting Yes
> Shared Yes
> JobSheets none none
> QuotaPeriod 0
> PageLimit 0
> KLimit 0
> AllowUser root
> AllowUser davidrjr
> OpPolicy default
> ErrorPolicy stop-printer
> </Printer>
>
> If anybody has additional insight, I'd sure appreciate it.
>
> Dave
>
> > Roland
>
>
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>

IIRC, you should be able to actually write

echo "something" >> /dev/ulpt0

and it should print? Might be useful for testing and stuff.

Anyway, after a quick bit of googling around for your problem (I've had CUPS
problems many times in the past myself and I know how hard it can be) I
found this:

Here is a workaround:

In printers.conf () you will probably find a line like this:

DeviceURI usb:/dev/ulpt0

change usb: to file:, so that it looks something like this:

DeviceURI file:/dev/ulpt0

Then restart cups. Cups will not read any status information from the
printer, but at least it can print. Be warned about unknown side effects. :)

Jan-Espen Pettersen


( http://lists.freebsd.org/pipermail/freebsd-questions/2006-June/125703.html)

Christian Zachariasen


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