set volume on Mac using command

set-vol

#!/bin/bash
let now_vol=`osascript -e 'output volume of (get volume settings)'`
case $1 in
    up)
        let vol=$now_vol+10
        if [ "$vol" -gt 100 ] ; then
            vol=100
        fi
        osascript -e "set volume output volume $vol"
        echo "Volume: $vol"
    ;;
    down)
        let vol=$now_vol-10
        if [ "$vol" -lt 0 ] ; then
            vol=0
        fi
        osascript -e "set volume output volume $vol"
        echo "Volume: $vol"
    ;;
    [0-9]|[1-9][0-9]|100)
        osascript -e "set volume output volume $1"
        echo "Volume: $1"
    ;;
    mute)
        osascript -e 'set volume output muted true'
    ;;
    nomute)
        osascript -e 'set volume output muted false'
    ;;
    *)
        echo "useage:{up|down|0-100|mute|nomute}"
        exit 1
    ;;
esac
exit 0