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Comment by monitron | Hacker News Reader

This is cool. But it seems to me that this person's setup could benefit from a way for the computers to be notified that battery power would run out soon so that they could shut down cleanly. I have that going at home through a USB connection to a UPS...it would be harder to set it up with a central battery but they seem to be up to fun challenges :)

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(I'm this person.) It so happens that the solar inverter I'm using right now doesn't provide a data connection that I could use to shut down the computers cleanly.

But I should also clarify that my long-running fsck isn't always the result of an unclean shutdown. There's something about my combination of iSCSI+crypttab+NFS that causes fsck to be run too often—even if I shut down the machine cleanly while the NAS is running, it usually decides to fsck when it comes back up.

Something to investigate next winter, perhaps.

Hi :) Thanks for the awesome write-up. I understand...I have a few devices in my house that resist all attempts at integration. I have considered doing something totally ridiculous like setting up a Raspberry Pi with a camera and machine vision software to watch the LED displays on these devices to glean status information. Silly, but...

Interesting about fsck running for unclear reasons. "What is it up to now?" is a valid question at multiple levels!

> Thanks for the awesome write-up.

Glad you enjoyed it. :-)

> I have considered doing something totally ridiculous like setting up a Raspberry Pi with a camera and machine vision software to watch the LED displays on these devices to glean status information. Silly, but...

Ha! I actually have a PoE camera pointed at the display of my UPS. Here's what it looks like right now: https://toroid.org/misc/ups-display.jpg

Notice that horizontal blank row of dead pixels halfway down the right side of the display? The one that makes "54.6" look like "51.6"? That gap defeated my naïve five-minute attempt to use image recognition to extract the battery voltage.

I would be tempted to tie the LED lines to digital ins on an Arduino. I'm betting some finagling with the display data lines could get you the information from the display, as well.

Depending on how the cabling to that display works, you might be able to do all of that without having to disable the display.

You could run a cheap/small UPS off your main stores maybe? That could possibly provide the signal and management

Whats up with the "[f]" in your grep command?

    grep '[f]sck'

It keeps the grep command itself from showing up in the output.

Ooh, that's very cute! I usually throw a "| grep -v grep" on the end, but I'm gonna try to remember this.

Better to remember pgrep, instead of an incremental change that you'll find still has problem cases (such as matching usernames).

* http://mywiki.wooledge.org/ProcessManagement#But_I.27m_on_so...

M. Wooledge's description of ps options is not quite accurate, but that is incidental to xyr main point.

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