On Linux, if two copies of a driver are competing for the UPS, these messages will appear in dmesg:
usbfs: process 29641 (usbhid-ups) did not claim interface 0 before use
This can be a symptom of a source install conflicting with a package install. There is a rudimentary locking mechanism in NUT, but there is a chance that the packages might not use the same directory as the NUT default, and the conflict will be reported by the kernel.
Also see above about conflicts between driver instances started by a service
management framework like systemd and started manually (e.g. with upsdrvctl
).