As specified on the documentation (http://documentup.com/arturadib/shelljs), I tried installing shelljs locally (given that the option [-g] looks optional), but I am having this issue on the console:

npm WARN package.json shelljs@0.0.0 No repository field.
npm WARN package.json shelljs@0.0.0 No README data
npm WARN install Refusing to install shelljs as a dependency of itself

Is this behavior by design? Should I install shelljs always globally?
Thanks