This script iTunes(Music.app) play, pause, next track, back track and return state.

iTunes.sh

#!/bin/sh

# @(#) This script Music.app play, pause, next track, back track and return state.
# @(#) Support macOS Catalina version.20191116

if [ -z "$1" ]; then
  echo "Argument is missing!"
  exit 1
elif [ "$1" == "play" ]; then
  music_run=`osascript -e 'application "Music" is running'`
  if [ "$music_run" == "false" ]; then
    osascript -e 'tell application "Music" to activate'
  fi
  osascript -e 'tell application "Music" to play'
elif [ "$1" == "pause" ]; then
  music_run=`osascript -e 'application "Music" is running'`
  if [ "$music_run" == "true" ]; then
    osascript -e 'tell application "Music" to pause'
  fi
elif [ "$1" == "next" ]; then
  osascript -e 'tell application "Music" to next track'
elif [ "$1" == "back" ]; then
  osascript -e 'tell application "Music" to back track'
elif [ "$1" == "status" ]; then
  osascript ./iTunes_status.scpt
else
  echo "Invalid argument!"
  exit 1
fi

iTunes_status.scpt

if application "Music" is running then
  tell application "Music"
    set a to player position as text
    delay 1
    set b to player position as text
    if a = b then
      --log "status:pause"
      return 0
    else
      --log "status:play"
      return 1
    end if
  end tell
else
  --log "Music.app not working"
  return 0
end if