You have to be inside an angular-cli project in order to use the serve command --angular4

错误：

解决：

按照下面这篇博客操作后还是有问题
【Angular4】You have to be inside an Angular CLI project in order to use the serve command
于是请来了大神，几个命令解决了，步骤：删除node库，重装npm；命令依次输入npm install rimraf -g ; rimraf node_modules ; npm install，如下图

然后再输入ng serve，启动成功。