Async example calling exec

gistfile1.txt

for ( var i = 0; i < total_tiles; i++ ) {
  var filename = "tiles_" + i + ".png"; // current filename
  var target = "map_" + column + "_" + row + ".png" // new filename

  var cmd = "file " + i + " cmd> cp -f gen/" + filename + " mappy/" + target;
  console.log(cmd);

  //taskList.push(async.apply(child_process.exec, cmd));

  taskList.push(function(command) {
    return function(callback) {
      console.log('calling cmd ' + command);
      child_process.exec(command, callback);
    };
  }(cmd));

  //child_process.exec(cmd);

  // work out next step
  column++;
  if ( column >= tiles_per_column ) {
    column = 0;
    row++;
  }
}