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.
