Re: non installed printer can not be removed
On Sun 19 Jun 2022 at 18:01:36 -0400, The Wanderer wrote:
> On 2022-06-19 at 15:47, Brian wrote:
>
> > On Sun 19 Jun 2022 at 14:54:58 -0400, The Wanderer wrote:
> >
> >> On 2022-06-19 at 14:50, Brian wrote:
>
> >>> What does being "precious" involve?
> >>
> >> I'm less certain about this, but my guess is that it means that
> >> CUPS insists on having these detected printers listed as available,
> >> rather than permitting them to be deleted from the list of
> >> available printers and having them remain that way.
> >
> > You (or the OP) would have to say what is meant by "delete". CUPS
> > essentially *discover* printers. It is why it exists. Is that not
> > wanted?
>
> I understand the reason for CUPS' existence to be, not *discovering
> printers*, but *facilitating the ability to print*. That could involve
> discovering printers and presenting them as available, or it could
> involve only presenting as available a list of printers that have been
> entered into CUPS or otherwise set up in CUPS by some more manual means.
> (Among perhaps other possibilities.)
The ability to print to an IPP printer involves discovering its URI.
CUPS gets the URI via avahi-daemon whether it is an on-demand or
manual queue.
> Certainly at my workplace I understand that our Macs use CUPS for
> (network) printing, but at least at one point in our history (within the
> past decade), we had to go in and define each printer by IP address in
> CUPS on each Mac (or on the central machine which would be replicated to
> the others).
Setting up a manual queue for a moden printer is still available but
is unnecessary. 'lpstat -e' showves every printer on a subnet and they
should (barring bugs) appear in an application's print dialog without
any intervention.
> I can certainly see it as being reasonable to want to be able to have
> CUPS perform printer discovery *on request*, and manually choose which
> of the discovered printers to add to the list of ones that will be
> remembered and shown as available when printing, but not have CUPS run
> discovery *automatically* and *automatically* add every discovered
> printer to that list. (I don't know with any confidence whether CUPS
> does the latter; I don't run it in enough environments with enough
> different available printers to have been able to make an assessment.
> However, I do have the impression that it may.)
You can control whether Avahi browses for printers or not but cannt
make it selective in its browsing. DNS-SD is an all-or-nothing public
service discovery protocol. Perhaps think of the display screens at
airports.
I beleive filtering of a printer list using LDAP is something being
considered for inclusion in a future CUPS.
--
Brian.
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