执行 node server.js

报错：
Error: listen EADDRINUSE :::80
at Server.setupListenHandle [as _listen2] (net.js:1360:14)
at listenInCluster (net.js:1401:12)
at Server.listen (net.js:1485:7)
at Object. (/Users/jokky/work/safety/server.js:27:35)
at Module._compile (module.js:653:30)
at Object.Module._extensions…js (module.js:664:10)
at Module.load (module.js:566:32)
at tryModuleLoad (module.js:506:12)
at Function.Module._load (module.js:498:3)
at Function.Module.runMain (module.js:694:10)
at startup (bootstrap_node.js:204:16)
at bootstrap_node.js:625:3

我是用的node 6.4.1
nodemon 1.18.9