~/.bin/warn-if-low.sh: Warn if low on battery (an not connected)

Use it in your crontab. I have it running every minute.

.bin/warn-if-low.sh

@@ -0,0 +1,14 @@
#!/bin/bash
# Warn if the battery status is lower than 10%
charge_path="/sys/class/power_supply"
charge_full=`cat $charge_path/BAT0/charge_full`
charge_now=`cat $charge_path/BAT0/charge_now`
charge_rate=$(($charge_now * 100 / $charge_full ))
online=`cat $charge_path/AC0/online`
if [ "$online" = "0" -a $charge_rate -lt 10 ]; then
	DISPLAY=:0 zenity --error --text "Whoopey: You're low on energy (only $charge_rate% left)!"
fi