Call an external command line tool - Example with lilypond

processLilypond.js

//---------------------------------------------------------
//    init
//    this function will be called on startup of mscore
//---------------------------------------------------------

function init()
      {
      }

//-------------------------------------------------------------------
//    run
//    this function will be called when activating the
//    plugin menu entry
//-------------------------------------------------------------------

function run()
      {
      // temp folder for user  C:\Users\<USERNAME>\AppData\Local\Temp on windows
      var path = QDir.tempPath(); // 
      var file = path + "/score.ly";
      curScore.save(file, "ly");
      
      //See http://doc.qt.nokia.com/latest/qprocess.html
      var lilypond = new QProcess();
      var args = new Array();
      args[0]= "-o";
      args[1]= path;
      args[2]= file;
      
      // if you want to log output
      //lilypond.setStandardOutputFile("stdout.txt");
      //lilypond.setStandardErrorFile("stderr.txt");

      lilypond.start("lilypond", args );
      lilypond.waitForStarted();
      lilypond.waitForFinished();
      }

//---------------------------------------------------------
//    menu:  defines were the function will be placed
//           in the MuseScore menu structure
//---------------------------------------------------------

var mscorePlugin = {
      menu: 'Plugins.Lilypond process',
      init: init,
      run:  run
      };

mscorePlugin;