Can't install ionic - permission denied in terminal

Hi there, I am totally struggeling with this. No terminal user, this is my first time using it. I’ve installed node.js and npm and now cordova and ionic, but with ionic, I always get this output. Any help what this is and why?

$ sudo npm install ionic -g
/usr/local/bin/ionic -> /usr/local/lib/node_modules/ionic/bin/ionic

> node-sass@3.7.0 install /usr/local/lib/node_modules/ionic/node_modules/ionic-app-lib/node_modules/node-sass
> node scripts/install.js

shell-init: error retrieving current directory: getcwd: cannot access parent directories: Permission denied
          cwd = process.cwd();

Error: EACCES: permission denied, uv_cwd
    at Error (native)
    at Object.resolve (path.js:1144:25)
    at startup (node.js:104:32)
    at node.js:405:3
└── (empty)

npm ERR! Darwin 15.5.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "ionic" "-g"
npm ERR! node v5.11.1
npm ERR! npm  v3.8.6

npm ERR! node-sass@3.7.0 install: `node scripts/install.js`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the node-sass@3.7.0 install script 'node scripts/install.js'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the node-sass package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     node scripts/install.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs node-sass
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls node-sass
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /npm-debug.log
npm ERR! code 1