#!/bin/bash

get_state() {
	echo "$(amixer cget name='Master Playback Switch' | grep "values=o" | cut -d= -f2 | cut -d, -f1)"
}

get_opposite() {
	if [ $1 = "on" ]; then
		echo "off"
	else
		echo "on"
	fi
}

amixer cset name='Master Playback Switch' $(get_opposite $(get_state))