node_modules下.bin目录下有一个webpack.cmd脚本文件，组装定位了要执行的webpack.js文件

"%~dp0\node.exe"  "%~dp0\..\webpack\bin\webpack.js" %*

将启动文件指向了webpack目录下的bin\webpack.js。

在webpack.js文件中，有一个runCommond办法和isInstalled判断包是否装置函数,

const runCommand = (command, args) => {    const cp = require("child_process");    return new Promise((resolve, reject) => {        const executedCommand = cp.spawn(command, args, {            stdio: "inherit",            shell: true        });        executedCommand.on("error", error => {            reject(error);        });        executedCommand.on("exit", code => {            if (code === 0) {                resolve();            } else {                reject();            }        });    });};const isInstalled = packageName => {    try {        require.resolve(packageName);        return true;    } catch (err) {        return false;    }};

installedClis获取曾经装置的cli，这外面重要的就是CLIs数组中第一行isInstalled("webpack-cli"),指向了webpack-cli。

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

接下来依据filter办法找到曾经安装包，解决了包门路，通过最初的require导入了wbpack-cli/bin/cli.js

    const path = require("path");    const pkgPath = require.resolve(`${installedClis[0].package}/package.json`);    // eslint-disable-next-line node/no-missing-require    const pkg = require(pkgPath);    // eslint-disable-next-line node/no-missing-require    require(path.resolve(        path.dirname(pkgPath),        pkg.bin[installedClis[0].binName]    ));

在wbpack-cli/bin/cli.js中，是一个IIFE,个别的cli文件中个别有二个操作，解决参数，将参数交给不同的逻辑（散发业务），文件中导入webpack，创立一个webpack实例。依据参数options创立一个compile实例，挂载钩子，

    const webpack = require("webpack");    let lastHash = null;    let compiler;    try {    compiler = webpack(options);    } catch (err) {    if (err.name === "WebpackOptionsValidationError") {        if (argv.color) console.error(`\u001b[1m\u001b[31m${err.message}\u001b[39m\u001b[22m`);        else console.error(err.message);        // eslint-disable-next-line no-process-exit        process.exit(1);    }    throw err;    }

在文件结尾处，就找到了webpack打包入口run办法

compiler.run((err, stats) => {    if (compiler.close) {        compiler.close(err2 => {            compilerCallback(err || err2, stats);        });    } else {        compilerCallback(err, stats);    }});