# OpenBSD
mute on:         mixerctl outputs.master.mute=off
mute off:        mixerctl outputs.master.mute=on
mute toggle:     mixerctl -t outputs.master.mute
increase master: mixerctl outputs.master=+2,0
decrease master: mixerctl outputs.master=-2,0

# FreeBSD
mute on:         mixer vol 0
mute off:
mute toggle:
increase master: mixer vol +2
decrease master: mixer vol -2