Sample gruntfile

grunt.js

/*global module:false*/
module.exports = function(grunt) {

  var SRC_CSS   = 'src/css/',
      SRC_JS    = 'src/js/',
      BUILD_CSS = 'css/',
      BUILD_JS  = 'js/';


  // Project configuration.
  grunt.initConfig({
    pkg: '<json:package.json>',
    meta: {
      banner: '/*! <%= pkg.title || pkg.name %> - v<%= pkg.version %> - ' +
        '<%= grunt.template.today("yyyy-mm-dd") %>\n' +
        '<%= pkg.homepage ? "* " + pkg.homepage + "\n" : "" %>' +
        '* Copyright (c) <%= grunt.template.today("yyyy") %> <%= pkg.author.name %>;' +
        ' Licensed <%= _.pluck(pkg.licenses, "type").join(", ") %> */'
    },
    
    min: {
      js: {
        src: '<config:concat.js.dest>',
        dest: BUILD_JS + 'all.js'
      }
    },
    cssmin: {
      css: {
        src: '<config:concat.css.dest>',
        dest: BUILD_CSS + 'all.css'
      }
    },
    
    lint: {
      files: [SRC_JS + 'app/**/*.js']
    },
    watch: {
      js: {
        files: '<config:concat.js.src>',
        tasks: 'concat:js'
      },
      less: {
        files: '<config:concat.less.src>',
        tasks: 'concat:less less concat:css'
      }
      
    },
    jshint: {
      options: {
        curly: true,
        eqeqeq: true,
        immed: true,
        latedef: true,
        newcap: true,
        noarg: true,
        sub: true,
        undef: true,
        boss: true,
        eqnull: true,
        browser: true
      },
      globals: {
        jQuery: true
      }
    },
    less: {
      css: {
        src: SRC_CSS + 'app/base.less',
        dest: SRC_CSS + 'app/base.css'
      }
    },
    concat: {
      
      less: {
        src: [SRC_CSS + 'libs/bootstrap.less',
              SRC_CSS + 'less/styles.less'],
        dest: SRC_CSS + 'app/base.less',
      },
      
      css: {
        src: [SRC_CSS + 'libs/*.css',
              SRC_CSS + 'app/*.css'],
        dest: BUILD_CSS + 'all.css'
      },
      js: {
        src: [SRC_JS + 'libs/jquery-1.7.2.js',
              SRC_JS + 'libs/jquery.follower.js',
              SRC_JS + 'libs/jquery.fancybox.js',
              SRC_JS + 'app/app.js'],
        dest: BUILD_JS + 'all.js'
      },
    }

  });



  grunt.loadNpmTasks('grunt-less');
  grunt.loadNpmTasks('grunt-css');

  // Default task.
  grunt.registerTask('default', 'lint concat:less less concat min cssmin');
  grunt.registerTask('hint', 'lint');
  grunt.registerTask('minify', 'concat:less less concat min cssmin');


};

package.json

{
  "name": "Sitename",
  "version": "1.0.0",
  "dependencies" : {
    "grunt-less":  ">0.0.0",
    "grunt-css":   ">0.0.0"
  }
}