On Tue 29 Oct 2019 at 15:11:18 +0000, Drew Arnett wrote: > Not exactly cross purposes. I'm encountering the cups error before I > get the chance to even select any specific printer or printer > interface.
I had realised what was going on. My inquiry was a gentle one because I thought there would possibly be a way round the problem, depending on the printer model. It doesn't matter now because the issue is not ammenable to being tackled in this way (please see below). > Given that this is with Debian live[1], I'll be using it, > as I have in the past, with USB or network printers or even a parallel > port printer if I have one. The test setup I have right now for > reporting on and researching this problem has both USB and network > printers available. The PC looks like it has a parallel port and I do > have a parallel port printer nearby if that helps. I definitely would > like to figure out what's wrong, as Debian live is a useful tool, and > it was great when printing worked with it. (I don't care if it's a > real bug or just a dumb user mistake to figure out and share.) I do not think it is a user mistake. But (see below) Debian live does not seem to have kept up with changes in buster. > The computer, printer, and network haven't changed since this was > working with the last Debian 9 point release XFCE live image. > > Let me walk through the scenario again, with a more step by step > detail. (And please ask if I should flesh out anything even further!) Your attention to detail makes the issue easy to follow. > Step 1: Boot debian-live-10.1.0-amd64-xfce.iso[2]. (Image written to > read only thumb drive. Thumb drive read back to verify checksum and > image integrity.) Packages in this image are listed in [3]. > > Step 2: sudo apt-get update > > Note: no sudo apt-get upgrade this time just to keep it simple. Upgrading is generally not a bad move. > Note: sources.list only contains one line: deb > http://deb.debian.org/debian/ buster main Ok. > Step 3: sudo apt-get install cups > > Note: cups server was not installed, so need to install. Same with > Debian 9 live. Additional packages apt-get installed are in [3]. > Could there be something else required? No printing system on Debian live? Deary me! It should be there and functional. Why make users jump through hoops to print? > Step 4: sudo /etc/init.d/cups start 'sudo systemctl start cups' here. And, in addition, cups should be started when cups-daemon is installed. I am beginning to wonder what Debian live is playing at. > Note: no custom configuration changes before starting cups server. > Wasn't required for Debian 9 live. And should never be required. > Note: at this point, cups has 8 lines in /var/log/cups/error_log. > > E [29/Oct/2019:14:40:35 +0000] Unable to open > \"/usr/share/cups/mime\": Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open \"/etc/cups\": > Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open > \"/usr/share/cups/mime\": Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open \"/etc/cups\": > Permission denied > E [29/Oct/2019:14:40:35 +0000] cupsdLoadBanners: Unable to open > banner directory "/usr/share/cups/banners": Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open spool directory > "/var/spool/cups": Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open directory > "/var/spool/cups/tmp" - Permission denied > E [29/Oct/2019:14:40:35 +0000] Unable to open directory > "/var/cache/cups" - Permission denied > > Those look dire. New with buster? I think this is the crux of the issue. apparmor is now installed by default. See what the journalctl output gives you. > ls -ld on those directories shows: > drwxr-xr-x 2 root root 240 Oct 29 14:40 /usr/share/cups/mime > drwxr-xr-x 5 root lp 220 Oct 29 14:40 /etc/cups > drwxr-xr-x 2 root root 180 Oct 29 14:40 /usr/share/cups/banners > drwxrwx--T 2 root lp 40 Aug 21 07:43 /var/spool/cups/tmp > drwxrwx--- 3 root lp 80 Oct 29 14:40 /var/cache/cups Nothing wrong there AFAICT. > Note: at this point, cupsd process is running as root. > > Step 5: XFCE menu: Applications: Settings: Print Settings > > ps -efd | grep user | grep print suggests that starts: > user 1125 987 0 02:37 ? 00:00:02 /usr/bin/python3 > /usr/share/system-config-printer/applet.py > user 6263 1075 2 14:47 ? 00:00:01 /usr/bin/python3 > /usr/share/system-config-printer/system-config-printer.py > > Note: The dialog box for the print settings comes up ok. There is a > cupsd access log message showing the connection made without error. > > Step 6: In the print settings application, click on add printer. It > asks for username & password authentication. It did not do this with > buster 9. Cancel. > > Note: is there a new need for user to be member of lp or lpadmin > group? user is member of neither. You are using system-config-printer. Please see https://wiki.debian.org/CUPSPrintQueues#scp > Step 7: sudo adduser user lp A security risk. That user can now read what I send to the printing system. > Step 8: sudo adduser user lpadmin > > Step 9: logout and back in. Verify user now member of those groups as well. > > Step 10: start prnt settings application again. Select add printer. > > Note: no longer get the request to authenticate. However, now get an > error dialog popup that says: > "CUPS server error > There was an error during the CUPS operation: 'Internal Server Error'." > With cancel & retry buttons. Probably a consequence of having apparmor on the system. [...] Cheers, Brian.
