execute script on low UPS power

Question

I have attached my UPS to ubuntu and it's recognised. However I don't like the options that I see in ubuntu power settings. I have another PC also attached to same UPS. So I want ubuntu desktop to execute script when power is about 50% so my second pc can also properly hibernate. And then I can hibernate my ubuntu PC with same script.

Is it possible to do that in the way that is not breaking ubuntu implpementation of UPS monitor? I have read that I can install nut but I have some errors, maybe it's a conflict

● nut-monitor.service - Network UPS Tools - power device monitor and shutdown controller
   Loaded: loaded (/lib/systemd/system/nut-monitor.service; enabled; vendor preset: enabled)
   Active: failed (Result: protocol) since Sat 2019-07-13 02:09:46 MSK; 11ms ago
  Process: 13906 ExecStart=/sbin/upsmon (code=exited, status=0/SUCCESS)

Maybe I can catch some dmesg message or check the status of UPS with some native tool?

score 2 · Accepted Answer · answered Jul 13 '19 at 01:02

Ubuntu automatically keeps track of all batteries status:

The same information displayed in the GUI screen above can also be accessed from your terminal / shell / bash script (they are all sort of the same thing in many ways).

To get the same information from CLI use:

$ upower -i $(upower -e | grep -i UPS)
  native-path:          /sys/devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1.2/1-1.2:1.0/usbmisc/hiddev2
  vendor:               CPS
  model:                CP550HGa
  serial:               BFBB104#BI1.g
  power supply:         yes
  updated:              Fri 12 Jul 2019 06:35:56 PM MDT (12 seconds ago)
  has history:          yes
  has statistics:       yes
  ups
    present:             yes
    state:               fully-charged
    warning-level:       none
    time to empty:       25.5 minutes
    percentage:          100%
    icon-name:          'battery-full-charged-symbolic'

Then to narrow it down to percentage use:

$ upower -i $(upower -e | grep -i UPS) | grep -i percentage
    percentage:          100%

Then to extract the second column use:

$ upower -i $(upower -e | grep -i UPS) | grep -i percentage | cut -d':' -f2
          100%

Then to extract only digits and eliminate leading spaces and trailing % use:

$ upower -i $(upower -e | grep -i UPS) | grep -i percentage | sed 's/[^0-9]*//g'
100

Now assign what you want to a variable and display it:

$ PERCENT=$(upower -i $(upower -e | grep -i UPS) | grep -i percentage | sed 's/[^0-9]*//g')
$ echo $PERCENT
100

Next step is to write a script something like this

#!/bin/bash

while true; do
    PERCENT=$(upower -i $(upower -e | grep -i UPS) | grep -i percentage \
        | sed 's/[^0-9]*//g')
    if [[ "$PERCENT" -lt 50 ]] ; then
        # email my cell phone
        mail -s "Electricity grid has shut down, run home" someone@example.com
        # text my cell phone
        curl -X POST https://textbelt.com/text --data-urlencode \
            phone="999-333-4567" --data-urlencode \
            message="Electricity grid has shot down, run home" -d key=textbelt
    fi
    sleep 300 # Sleep for 5 minutes to reduce resource usage
done

emailing cell phone: Use mail command
texting cell phone: How can I send mobile text message from terminal?

This is a script I would use, in your case adapt it to hibernate (I have a laptop so I never hibernate). My UPS is for window fan, not laptop which has it's own battery and is suspended when I'm at work. Technology can be used differently by different people.

execute script on low UPS power

1 Answers1