Copy new file updates to directory with Grunt

Gruntfile.js

var date = new Date();
module.exports = function(grunt) {
  grunt.initConfig({
    watch: {
      models: {
        files: ['application/models/**/*.php'],
        tasks: ['copyTask'],
        options: {
          spawn: false,
        },
      },
      views: {
        files: ['application/views/**/**/*.tpl'],
        tasks: ['copyTask'],
        options: {
          spawn: false,
        },
      },
      controllers: {
        files: ['application/controllers/**/*.php'],
        tasks: ['copyTask'],
        options: {
          spawn: false,
        },
      },
      language: {
        files: ['application/language/**/*.php'],
        tasks: ['copyTask'],
        options: {
          spawn: false,
        },
      },
    },
    copy: {
      main: {
        src: '',
        dest: 'updates/',
      },
    },
    compress: {
      main: {
        options: {
          archive: 'updates/update-'
                    +date.getDate()+'-'
                    +(date.getMonth()+1)+'-'
                    +date.getFullYear()+'-'
                    +date.getHours()+'.'
                    +date.getMinutes()
                    +'.zip',
        },
        files: [
          {
            expand: true,
            cwd: 'updates/',
            src: ['**'],
            dest: 'updates/',
          }
        ]
      }
    }
  });
  var newFile = '';
  grunt.event.on('watch', function(action, filepath, target) {
    grunt.log.writeln(target + ': ' + filepath + ' has ' + action);
    newFile = filepath;
    newFile = newFile.replace('\\', "/");
  });
  grunt.registerTask('copyTask', function() {
    grunt.config.set('copy.main.src', newFile);
    grunt.task.run('copy:main');
  });
  grunt.loadNpmTasks('grunt-contrib-compress');
  grunt.loadNpmTasks('grunt-contrib-copy');
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.registerTask('default', 'watch');
  grunt.registerTask('build-update', 'compress:main');
};