问在truffle.js中定义网络时语法错误

EN

dwayne@dwayne-UX305CA:~/HelloTruffle$ cat truffle.js
//module.exports = {
  // See 
  // to customize your Truffle configuration!
//};

networks: {
  ganache: {
      host: "localhost",
      port: 7545,
      network_id: "*"
  }
}


dwayne@dwayne-UX305CA:~/HelloTruffle$ truffle migrate --reset --compile-all --network ganache
/home/dwayne/HelloTruffle/truffle.js:9
      port: 7545,
          ^

SyntaxError: Unexpected token :
    at createScript (vm.js:80:10)
    at Object.runInThisContext (vm.js:139:10)
    at Module._compile (module.js:616:28)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Module.require (module.js:596:17)
    at require (internal/module.js:11:18)
    at Function.Config.load (/usr/lib/node_modules/truffle/build/webpack:/~/truffle-config/index.js:259:1)
    at Function.Config.detect (/usr/lib/node_modules/truffle/build/webpack:/~/truffle-config/index.js:248:1)
    at Object.run (/usr/lib/node_modules/truffle/build/webpack:/~/truffle-core/lib/commands/migrate.js:35:1)
    at Command.run (/usr/lib/node_modules/truffle/build/webpack:/~/truffle-core/lib/command.js:101:1)
    at Object. (/usr/lib/node_modules/truffle/build/webpack:/~/truffle-core/cli.js:16:1)
    at __webpack_require__ (/usr/lib/node_modules/truffle/build/webpack:/webpack/bootstrap b4601922d6f11f8bff0b:19:1)
    at /usr/lib/node_modules/truffle/build/webpack:/webpack/bootstrap b4601922d6f11f8bff0b:65:1
    at Object. (/usr/lib/node_modules/truffle/build/cli.bundled.js:71:10)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3

dwayne@dwayne-UX305CA:~/HelloTruffle$ truffle version
Truffle v4.1.11 (core: 4.1.11)
Solidity v0.4.24 (solc-js)