Works great, tweak if you use source compiled nagios

I installed on Ubuntu 18.04 from .deb file OK. Since I have source-built nagios in /usr/local, I had to link the executable to /usr/local/nagios/libexec and add ‘use lib “/usr/local/nagios/libexec” ;’ to Perl script.

Works like charm, supports even voltage ranges properly!

ie. try
check_nut_plus -d your_nut_ups -v “input.voltage=w245”

And it will correctly give warning for voltages outside 220-230 and critical for voltages outside 210-245.

Full marks, have been looking for similar for apcupsd, but NUT is the way to go.