Command "webpack-dev-server" not found. code example

Example 1: Error: Cannot find module 'webpack-dev-server'

npm install --save-dev webpack-dev-middleware webpack-hot-middleware

Example 2: webpack-dev-server command not found

npm install webpack-dev-server -g

Example 3: sh: webpack-dev-server: command not found

"scripts": {
  "start:dev": "webpack-dev-server"
}