[Nut-upsuser] Nut problems with Centos and Belkin UPS

Arjen de Korte nut+users at de-korte.org
Tue Nov 27 07:48:20 UTC 2007

> I note though - that in my system - the usb device number seems rather
> erratic. Over the past day or so - the usb device number of the UPS has
> been increasing (possibly whenever I kill the processes trying to attach
> to it??) I am confident that i have not removed the connector or
> rebooted the system or powered off the UPS - but the device number
> originally reported as 4 and today it was up to 14.
> Today I also tried some experiments where I changed the permissions so
> that nut was working - then unplugged the usb cable, then plugged it
> back into the same connector. The device number increased from 4 to 5
> and I had to fix the permissions again.
> How much of this behaviour is as you would expect?

This is not uncommon. When the connection is dropped, the USB devices will
be enumerated again. Depending on your hardware and environment, this may
never happen or as often as every thirty minutes (or more). There is no
way to tell. That's why manually changing the permissions of USB devices
doesn't work in most (if not all) cases.

> What do you think caused the device number to increase without me
> removing the cable or rebooting?

EMI, a momentary glitch in the UPS causing the controller to restart,

> Is it normal that the number will change when I unplug/replug?


> Arjen refered to "hotplugging/udev" scripts. Where should these be? I
> wasn't able to find them anywhere - but maybe I am looking for the wrong
> thing in the wrong place.

Current kernels usually have udev. The script for that is located in
'scripts/udev' in the NUT sources and will be automatically installed. On
your system, it usually lives in /etc/udev/rules.d/.

Best regards, Arjen

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