webpack -v 提示 One CLI for webpac

npm install --save-dev webpack -g
输入以上命令后: webpack -v 提示:

One CLI for webpack must be installed. These are recommended choices, delivered as separate packages:

• webpack-cli (https://github.com/webpack/webpack-cli)
  The original webpack full-featured CLI.
• webpack-command (https://github.com/webpack-contrib/webpack-command)
  A lightweight, opinionated webpack CLI.
  We will use "yarn" to install the CLI via "yarn add -D".
  Which one do you like to install (webpack-cli/webpack-command):

需要安装 webpack-cli：

解决：
npm install --save-dev webpack-cli -g