Unfortunately, what’s missing is provision for unmounting the stick when the backup is complete, and some way of notifying the user that it is safe to remove it.
In a non-GUI environment, then I guess if they install "Policy Mount<https://linux.die.net/man/1/pmount>"... sudo apt install pmount ...then use the pumount<https://linux.die.net/man/1/pumount> command line utility of the pmount application. The pumount command could be invoked with a bash script to do the unmounting of the USB drive without requiring priv. I recently opted for... https://github.com/raamsri/automount-usb ...as a better tool for mounting USB drives over... usbmount<https://github.com/rbrito/usbmount> - automatically mount and unmount USB mass storage devices I combine automount-usb with pumount to do both the automatic mounting and manual unmounting of USB drives on a Debian server. cheers, Ian.