Simple command line iTunes controller

itunes.sh

#!/bin/bash
#
####################################
# Music Command Line Control v1.0
# written by David Schlosnagle
# created 2001.11.08
# edit    2010.06.01 Rahul Kumar
# edit    2013.08.09 Huw Rowlands
# edit    2019.12.19 Huw Rowlands - Updated to Catalina (Music.app)
####################################

showHelp() {
    echo "-----------------------------";
    echo "Music Command Line Interface";
    echo "-----------------------------";
    echo "Usage: $(basename "$0") <option>";
    echo;
    echo "Options:";
    echo " status   = Shows Music's status, current artist and track.";
    echo " pp       = (play-pause) Start playing if paused, otherwise pause.";
    echo " play     = Start playing.";
    echo " pause    = Pause playing.";
    echo " next     = Go to the next track.";
    echo " prev     = (backtrack) Go to the beginning of current track or previous track if already at the start.";
    echo " last     = Go to the previous track and start playing."
    echo " mute     = Mute Music's volume.";
    echo " unmute   = Unmute Music's volume.";
    echo " vol up   = Increase Music's volume by 10%";
    echo " vol down = Increase Music's volume by 10%";
    echo " vol #    = Set Music's volume to # [0-100]";
    echo " stop     = Stop Music.";
    echo " quit     = Quit Music.";
    echo " playlist = Show playlists saved in Music.";
    echo " tracks   = Show tracks for current or given playlist.";
    echo " shuf     = Shuffle current playlist";
    echo " nosh     = Do not shuffle current playlist";
}

showStatus() {
    state=$(osascript -e 'tell application "Music" to player state as string');
    echo "Music is $state.";
}

showPlaying() {
    state=`osascript -e 'tell application "Music" to player state as string'`;
    if [ $state = "playing" ]; then
        artist=`osascript -e 'tell application "Music" to artist of current track as string'`;
        track=`osascript -e 'tell application "Music" to name of current track as string'`;
        echo "$artist - $track";
    fi
}

if [ $# = 0 ]; then
    showPlaying;
fi

while [ $# -gt 0 ]; do
    arg=$1;
    case $arg in
        "status" )
            showStatus;
            showPlaying;
            break ;;

        "pp" | "playpause" )
            osascript -e 'tell application "Music" to playpause';
            break ;;

        "play"    )
            osascript -e 'tell application "Music" to play';
            break ;;

        "pause"    )
            osascript -e 'tell application "Music" to pause';
            break ;;

        "next"    )
            osascript -e 'tell application "Music" to next track';
            showPlaying;
            break ;;

        "prev" | "previous" | "backtrack" )
            osascript -e 'tell application "Music" to back track';
            showPlaying;
            break ;;

        "last"    )
            osascript -e 'tell application "Music" to previous track';
            showPlaying;
            break ;;

        "rewind"  )
            osascript -e 'tell application "Music" to refresh';
            showPlaying;
            break ;;

        "mute"    )
            osascript -e 'tell application "Music" to set mute to true';
            break ;;

        "unmute" )
            osascript -e 'tell application "Music" to set mute to false';
            break ;;

        "vol"    )
            vol=`osascript -e 'tell application "Music" to sound volume as integer'`;
            if [ $2 = "up" ]; then
                newvol=$(( vol+10 ));
            elif [ $2 = "down" ]; then
                newvol=$(( vol-10 ));
            elif [ $2 -gt 0 ]; then
                newvol=$2;
            fi
            osascript -e "tell application \"Music\" to set sound volume to $newvol";
            break ;;

        "stop"    )
            osascript -e 'tell application "Music" to stop';
            break ;;

        "quit"    )
            osascript -e 'tell application "Music" to quit';
            break ;;

        "albums"   )
            osascript -e 'tell application "Music"' -e 'set allAlbums to (get album)' -e 'end tell';
            break;;

        "playlist" )
            if [ -n "$2" ]; then
                echo "Changing Music playlists to '$2'...";
                osascript -e 'tell application "Music"' -e "set new_playlist to \"$2\" as string" -e "play playlist new_playlist" -e "end tell";
                break ;
            else
                # Show available Music playlists.
                echo "Playlists:";
                osascript -e 'tell application "Music"' -e "set allPlaylists to (get name of every playlist)" -e "end tell";
                break;
            fi
            break;;

        "shuf" ) echo "Shuffle is ON. (to turn off: `basename $0` nosh)";
            osascript -e 'tell application "Music" to set shuffle of current playlist to 1';
            break ;;

        "nosh" ) echo "Shuffle is OFF. (to turn on: `basename $0` shuf)";
            osascript -e 'tell application "Music" to set shuffle of current playlist to 0';
            break ;;

        "tracks" )
            if [ -n "$2" ]; then
                osascript -e 'tell application "Music"' -e "set new_playlist to \"$2\" as string" -e " get name of every track in playlist new_playlist" -e "end tell";
                break;
            fi
            osascript -e 'tell application "Music" to get name of every track in current playlist';
            break ;;

        "help" | * )
            showHelp;

            break ;;
    esac
done