I was trying to create a simple ASP.Net 5 project by using generator like Yeoman on my Mac. The instructions on ASP.Net docs website are simple and easy to follow. However I encountered a permission denied error on npm install for Yeoman.
Initially I thought I was not running an updated npm version so I tried to execute npm upgrade, but it did not work. I also tried to install again npm getting the installing from nodejs.org but the same error occurs.
Looking closely at the log, it was a permission error on a mkdir on /usr/local/bin folder. This was verified when I go to that folder and tried to create a folder but a permission error occurs. Getting closer to the root of the problem!
When I looked into the owner and group permissions in the folder, the group owner for node_modules (where the install is targeting the mkdir) is a group name wheel. The group name wheel seems to have been related to the roots of MAC OS X from Unix.
I issued two commands to gain permission to the folder.
sudo chgrp -R admin node_modules
sudo chown -R whoami nodel_modules
After gaining permission to the folder, I once again tried to install Yeoman using npm and the installation went through this time.
I hope this will save you time if ever you encounter the same problem on your way to trying more ASP.Net 5 samples.