执行一下命令
cd .\node_modules\.bin\

 CLIs = [
 {
  name: "webpack-cli",
  package: "webpack-cli",
  binName: "webpack-cli",
  alias: "cli",
  installed: isInstalled("webpack-cli"),
  recommended: true,
  url: "https://github.com/webpack/webpack-cli",
  description: "The original webpack full-featured CLI."
 },
 {
  // some coding
 }
];

const installedClis = CLIs.filter(cli => cli.installed);

if (installedClis.length === 0) {
 // some coding
 const question = `Do you want to install 'webpack-cli' (yes/no): `;
 // some coding
} else if (installedClis.length === 1) {
 const path = require("path");
 const pkgPath = require.resolve(`${installedClis[0].package}/package.json`);
 const pkg = require(pkgPath);
 console.log(path.resolve(
  path.dirname(pkgPath),
  pkg.bin[installedClis[0].binName]
 )) // E:\项目\webpack学习\node_modules\webpack-cli\bin\cli.js
 require(path.resolve(
  path.dirname(pkgPath),
  pkg.bin[installedClis[0].binName]
 ));
}

// node_modules/bin/cli.js
(function() {
 // 一大堆配置
 // something code ...
 yargs.parse(process.argv.slice(2), (err, argv, output) => {
  // something code ...
  function processOptions(options) {
   // 各种if else 过滤和配置
   // something code...
   const webpack = require("webpack");
   let compiler;
   try {
    // 运行webpack函数，返回一个compiler对象
    compiler = webpack(options); 
   } catch (err) {
    // something code...
   }
   // 执行compiler中的run，开始编译。
   compiler.run(compilerCallback);
  }
  processOptions(options);
 })
 // something code ...

})()

// node_modules/webpack/lib/webpack.js
const webpack = (options, callback) => {
 // some coding
 return compiler;
}
exports = module.exports = webpack;