osd-mpc-volume

#!/bin/sh
if [ -z "$1" -o -n "$2" ] ; then
	echo >&2 "Usage: $0 [+|-]<percentage>"
	exit 1
fi
mpc volume $1 | sed 's/.*volume: *\([0-9]\+\)%.*/\1/;t;d' | osdc 'MPC Volume' '' --percent=-