During the management of bug #891810 this exchange took place between Jonas Smedegaard and Didier 'OdyX' Raboud:
Le dimanche, 4 mars 2018, 13.54:27 h CET Jonas Smedegaard a écrit : > > Is PolicyKit _required_ for _all_ uses of hplip? > Good question. I'll admit I was put off my the (exhausting) 'systemd' > argument, and hadn't checked what exactly was done with PolicyKit. > My reading is that PolicyKit is used to grant privilege to run `hp-plugin` for > plugin download, thereby avoiding the need for sudo. > So no, definitely not _required_. I thought that is the function of Policykit in hplip too so put it to the test yesterday. stretch (base system only) was installed, upgraded to unstable and then hplip (without its recommended packages) was installed. 'hp-plugin -i' runs to completion after asking for and being provided with the root/superuser password. There is no difference in the outcome when policykit-1 is on the system. Maybe policykit-1 is used elsewhere with hplip (the GUI parts?) but I did not look at this extensively. What I did do was use 'hp-setup -i' without policykit-1 for a USB connected MFP. That gave error: No device selected/specified or that supports this functionality and journalctl indicated that permission to access the USB bus had been denied. Easily solved (as it is when sane-find-scanner gives a negative outcome) by installing libpam-systemd. (Or, interestingly, putting the user in the scanner group). The small amount I did indicates that having policykit-1 as only a Recommends: has not impacted unfavourably on the hplip package. Regards, Brian.