support inspect paths

packages/@vue/cli-service/lib/commands/inspect.js

@@ -1,23 +1,26 @@
 module.exports = (api, options) => {
   api.registerCommand('inspect', {
     description: 'inspect internal webpack config',
-    usage: 'vue-cli-service inspect [options] [...keys]',
+    usage: 'vue-cli-service inspect [options] [...paths]',
     options: {
       '--mode': 'specify env mode (default: development)'
     }
   }, args => {
     api.setMode(args.mode || 'development')
 
+    const get = require('get-value')
     const stringify = require('javascript-stringify')
     const config = api.resolveWebpackConfig()
-    const keys = args._
+    const paths = args._
 
     let res
-    if (keys.length) {
+    if (paths.length > 1) {
       res = {}
-      keys.forEach(key => {
-        res[key] = config[key]
+      paths.forEach(path => {
+        res[path] = get(config, path)
       })
+    } else if (paths.length === 1) {
+      res = get(config, paths[0])
     } else {
       res = config
     }

packages/@vue/cli-service/package.json

@@ -37,6 +37,7 @@
     "extract-text-webpack-plugin": "^3.0.2",
     "file-loader": "^1.1.6",
     "friendly-errors-webpack-plugin": "^1.6.1",
+    "get-value": "^2.0.6",
     "html-webpack-plugin": "^2.30.1",
     "husky": "^0.14.3",
     "javascript-stringify": "^1.6.0",