Spotify app controls in command line

spotifyctrl.sh

#!/bin/bash

SPOTIFYCMD="dbus-send --print-reply --dest=org.mpris.MediaPlayer2.spotify /org/mpris/MediaPlayer2 org.mpris.MediaPlayer2.Player."

function spotify_oper {
    ${SPOTIFYCMD}$1
}

case $1 in
    "play")
        spotify_oper "PlayPause"
        ;;
    "stop")
        spotify_oper "Stop"
        ;;
    "previous")
        spotify_oper "Previous"
        ;;
    "next")
        spotify_oper "Next"
        ;;
    *)
        echo "$0 play|pause|previous|next"
        ;;
esac