执行  
npm install –save-dev grunt 命令

遇到以下问题：

npm ERR! path /Users/aven/node-red/node_modules/onetime

npm ERR! code EACCES

npm ERR! errno -13

npm ERR! syscall access

npm ERR! Error: EACCES: permission denied, access ‘/Users/aven/node-red/node_modules/onetime’

npm ERR!  { Error: EACCES: permission denied, access ‘/Users/aven/node-red/node_modules/onetime’

npm ERR!   stack: ‘Err