Introduce a simple PoC for NUT readings seen in FUSE file system

[jimklimov]

Take advantage of the simple option in #2591 RFE, with https://github.com/vi/execfuse ("shell FUSE binding" project) successfully used for a simple and inefficient wrapper around upsc.

Tested on Linux and MacOS

[aquette]

Interesting @jimklimov
But to me, the real disruptive next step is still smartnut, as detailed in the pieces of specs I've started, and as started decades ago with the HAL connector. Pure async / event based, direct connection to the consuming busses (dbus, mqtt for HA and others, ...), ...

[jimklimov]

Yeah, this one is in no way fit for production at least as far as computational efficiency goes, just was a fun thought experiment turned into a code experiment after I told people about FUSE during lunch same day. It does work though, so is a decent demo of FUSE and the inceptions of filesystems in the UNIX world :)

A client similar to upsmon (maybe an optional new facet of it?) that would cache the info efficiently etc. may be another matter, especially for people who currently have to parse upsc outputs themselves e.g. for good old MRTG graphing or snmpagent representation....