运行 yo angular 出现如下提示：
$ yo angular
grunt-cli: The grunt command line interface. (v0.1.9)
Fatal error: Unable to find local grunt.
If you're seeing this message, either a Gruntfile wasn't found or grunt
hasn't been installed locally to your project. For more information about
installing and configuring grunt, please see the Getting Started guide:
http://gruntjs.com/getting-started
我们可以看到其中有在本地没有找到 grunt ，因此我们需要先在本地安装 grunt。
$ sudo npm install grunt --save-dev
运行以上命令，再去执行 yo angular 命令，就不会出现如上提示了。