I can confirm that clicking the refresh button in the title bar in gnome-software's update tab triggers packagekit to write /var/lib/PackageKit/prepared-update, which in turn makes the shutdown dialog offer to install updates before shutting down.
A few observations:
- contrary to what's stated in comment #2, I observe that ticking the checkbox results in updates being actually installed at shutdown (although I don't know what happens with updates that require user interaction)
- gnome-software's updates tab says the software is up-to-date, but there are actually 5 package updates available, and they are listed in /var/lib/PackageKit/prepared-update
- during my tests in a bionic VM, I also observed once that prepared-update file being created without interaction with gnome-software: I simply ran "sudo apt update" in a terminal window, then requested shutdown, and the dialog offered to install updates, so something else also triggered packagekit
I can confirm that clicking the refresh button in the title bar in gnome-software's update tab triggers packagekit to write /var/lib/ PackageKit/ prepared- update, which in turn makes the shutdown dialog offer to install updates before shutting down.
A few observations:
- contrary to what's stated in comment #2, I observe that ticking the checkbox results in updates being actually installed at shutdown (although I don't know what happens with updates that require user interaction)
- gnome-software's updates tab says the software is up-to-date, but there are actually 5 package updates available, and they are listed in /var/lib/ PackageKit/ prepared- update
- during my tests in a bionic VM, I also observed once that prepared-update file being created without interaction with gnome-software: I simply ran "sudo apt update" in a terminal window, then requested shutdown, and the dialog offered to install updates, so something else also triggered packagekit