pm2 观察报错时 pm2 start app.js --watch
pm2 start app.js --watch
[PM2][ERROR] Script already launched, add -f option to force re-execution
文章来自：http://www.cnblogs.com/winyh/p/6681265.html
pm2 start app.js --watch
[PM2][ERROR] Script already launched, add -f option to force re-execution