Beep on low battery (even when muted)

low-battery-beep.sh

#!/bin/bash
# Script to detect low battery volume while discharging and beep when so
# Prevent beeps with: `touch /tmp/no-beep'

while true
do
	status=$(cat /sys/class/power_supply/BAT0/status)
	full=$(cat /sys/class/power_supply/BAT0/energy_full)
	now=$(cat /sys/class/power_supply/BAT0/energy_now)
	low=$(echo "$now / $full < 0.1" | bc -l)

	if [ "$status" != "Charging" ] && [ "$low" == "1" ] && ! [ -f "/tmp/no-beep" ]; then
		# Play a warning sound, even when speakers are muted

		# Get current settings
		volume=$(pactl -- get-sink-volume 0 | grep -oEi '([0-9]+)%')
		mute=$(pactl -- get-sink-mute 0 | awk '{print $2}')

		# Unmute set volume
		pactl -- set-sink-mute 0 no
		pactl -- set-sink-volume 0 40%

		# Upload audio, play, remove
		pactl -- upload-sample /usr/share/sounds/freedesktop/stereo/suspend-error.oga error
		pactl -- play-sample error 0
		sleep 1.5
		pactl -- remove-sample error

		# Restore settings
		pactl -- set-sink-mute 0 $mute
		pactl -- set-sink-volume 0 $volume
	fi
	
	sleep 60
done