batenergy.sh

#!/usr/bin/env bash

FILE=/tmp/batenergy.dat

state=$1
sleep_type=$2

now=`date +'%s'`

read energy_now < /sys/class/power_supply/BAT0/energy_now #μWh
read energy_full < /sys/class/power_supply/BAT0/energy_full # μWh
read online < /sys/class/power_supply/AC/online


(($online)) && echo "Currently on mains."
((! $online)) && echo "Currently on battery."

case $state in
"pre")
	echo "Saving time and battery energy before sleeping ($sleep_type)."
	echo $now > $FILE
	echo $energy_now >> $FILE
	;;
"post")
	exec 3<>$FILE
	read prev <&3
	read energy_prev <&3
	rm $FILE
	time_diff=$(($now - $prev)) # seconds
	days=$(($time_diff / (3600*24)))
	hours=$(($time_diff % (3600*24) / 3600))
	minutes=$(($time_diff % 3600 / 60))
	echo "Duration of $days days $hours hours $minutes minutes sleeping ($sleep_type)."
	energy_diff=$((($energy_now - $energy_prev) / 1000)) # mWh
	avg_rate=$(($energy_diff * 3600 / $time_diff)) # mW
	energy_diff_pct=$(bc <<< "scale=1;$energy_diff * 100 / ($energy_full / 1000)") # %
	avg_rate_pct=$(bc <<< "scale=2;$avg_rate * 100 / ($energy_full / 1000)") # %/h
	echo "Battery energy change of $energy_diff_pct % ($energy_diff mWh) at an average rate of $avg_rate_pct %/h ($avg_rate mW)."
	;;
esac