A Gruntfile for Apache Cordova app development. Includes prepare, build and run tasks to mimic Cordova CLI commands. Usage: 'grunt <command> [platform]'. If no platform is provided Cordova will try to perform the task for all the installed platforms. Default task 'watch' watches for source changes and runs the prepare task.

Gruntfile.js

module.exports = function ( grunt ) {
  
  /** 
   * Load required Grunt tasks. These are installed based on the versions listed
   * in `package.json` when you do `npm install` in this directory.
   */
  
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-exec');

  /**
   * This is the configuration object Grunt uses to give each plugin its 
   * instructions.
   */
  var taskConfig = {
    /**
     *  The 'watch' task watches the files modified during development and runs
     *  the Cordova 'prepare' task which will copy your 'www' folder to the 
     *  platform specific build directory (ie: platforms/android/assets/www)
     */
    watch: {
      scripts: {
        files: [
          'www/*.html',
          'www/templates/**/*.tpl.html', 
          'www/js/**/*.js', 
          'www/css/**/*.css', 
          'www/spec/**/*.js',
          'www/res/**/*.*',
          'www/img/**/*.*', 
        ],
        tasks: ['prepare'],
        options: {
          spawn: false,
        },
      },
    },
    exec: {
      prepare: {
        command: function(platform){
          return 'cordova prepare' + ((platform) ? ' ' + platform : '');
        }
      },
      build: {
        command: function(platform){
          return 'cordova build' + ((platform) ? ' ' + platform : '');
        }
      },
      run: {
        command: function(platform){
          return 'cordova run' + ((platform) ? ' ' + platform : '');
        }
      }
    }
  };

  grunt.initConfig( grunt.util._.extend( taskConfig ) );

  grunt.registerTask( 'default', [ 'watch' ] );
  grunt.registerTask( 'prepare', ['exec:prepare'] );
  grunt.registerTask( 'build', ['prepare', 'exec:build' ] );
  grunt.registerTask( 'run', ['build', 'exec:run' ] );

};

Platform argument is not working as I expected. Sorry for that. Usage is grunt exec:[:platform]