Here are the messy results from the queries proposed earlier:
dpkg -l | grep foo
ii foomatic-db-compressed-ppds 20180306-1 all OpenPrinting printer support - Compressed PPDs derived from the database
ii printer-driver-foo2zjs 20170320dfsg0-4 amd64 printer driver for ZjStream-based printers
ii printer-driver-foo2zjs-common 20170320dfsg0-4 all printer driver for ZjStream-based printers - common files
dpkg -l | grep cups
ii bluez-cups 5.48-0ubuntu3.1 amd64 Bluetooth printer driver for CUPS
ii cups 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - PPD/driver support, web interface
ii cups-browsed 1.20.2-0ubuntu3 amd64 OpenPrinting CUPS Filters - cups-browsed
ii cups-bsd 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - BSD commands
ii cups-client 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - client programs (SysV)
ii cups-common 2.2.7-1ubuntu2.4 all Common UNIX Printing System(tm) - common files
ii cups-core-drivers 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - driverless printing
ii cups-daemon 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - daemon
ii cups-filters 1.20.2-0ubuntu3 amd64 OpenPrinting CUPS Filters - Main Package
ii cups-filters-core-drivers 1.20.2-0ubuntu3 amd64 OpenPrinting CUPS Filters - Driverless printing
ii cups-ipp-utils 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - IPP developer/admin utilities
ii cups-pk-helper 0.2.6-1ubuntu1.2 amd64 PolicyKit helper to configure cups with fine-grained privileges
ii cups-ppdc 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - PPD manipulation utilities
ii cups-server-common 2.2.7-1ubuntu2.4 all Common UNIX Printing System(tm) - server common files
ii libcups2:amd64 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - Core library
ii libcups2:i386 2.2.7-1ubuntu2.4 i386 Common UNIX Printing System(tm) - Core library
ii libcupscgi1:amd64 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - CGI library
ii libcupsfilters1:amd64 1.20.2-0ubuntu3 amd64 OpenPrinting CUPS Filters - Shared library
ii libcupsimage2:amd64 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - Raster image library
ii libcupsmime1:amd64 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - MIME library
ii libcupsppdc1:amd64 2.2.7-1ubuntu2.4 amd64 Common UNIX Printing System(tm) - PPD manipulation library
ii printer-driver-hpcups 3.17.10+repack0-5 amd64 HP Linux Printing and Imaging - CUPS Raster driver (hpcups)
ii python3-cups 1.9.73-2 amd64 Python3 bindings for CUPS
ii python3-cupshelpers 1.5.11-1ubuntu2 all Python utility modules around the CUPS printing system
This seems a trifle worrisome though:
dpkg -l grep avahi
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-==============-============-============-=================================
ii grep 3.1-2 amd64 GNU grep, egrep and fgrep
dpkg-query: no packages found matching avahi
Avahi was installed manually by me - though perhaps not correctly ??
I've done some searching & found nothing truly useful about it relating directly with Ubuntu and/or v18.04...any further clues for me on this, please ??
Thanks.