npm install -g less does not work: EACCES: permission denied

Question

Using sudo is not recommended. It may give you permission issue later. While the above works, I am not a fan of changing folders owned by root to be writable for users, although it may only be an issue with multiple users. To work around that, you could use a group, with 'npm users' but that is also more administrative overhead. See here for the options to deal with permissions from the documentation: https://docs.npmjs.com/getting-started/fixing-npm-permissions

I would go for option 2:

To minimize the chance of permissions errors, you can configure npm to use a different directory. In this example, it will be a hidden directory on your home folder.

Make a directory for global installations:

 mkdir ~/.npm-global

Configure npm to use the new directory path:

 npm config set prefix '~/.npm-global'

Open or create a ~/.profile file and add this line:

 export PATH=~/.npm-global/bin:$PATH

Back on the command line, update your system variables:

 source ~/.profile

Test: Download a package globally without using sudo.

npm install -g jshint

If still show permission error run (mac os):

sudo chown -R $USER ~/.npm-global   

This works with the default ubuntu install of:

sudo apt-get install nodejs npm

I recommend nvm if you want more flexibility in managing versions: https://github.com/creationix/nvm

On MacOS use brew, it should work without sudo out of the box if you're on a recent npm version. Enjoy :)

Run these commands in a terminal window (note: DON'T replace the $USER part... thats a linux command to get your user!):

sudo chown -R $USER ~/.npm
sudo chown -R $USER /usr/lib/node_modules
sudo chown -R $USER /usr/local/lib/node_modules

Mac OS X Answer

You don't have write access to the node_modules directory

npm WARN checkPermissions Missing write access to /usr/local/lib/node_modules

Add your User to the directory with write access

1. Open folder containing node_modules

   open /usr/local/lib/

2. Do a cmd+I on the node_modules folder to open the permission dialog
3. Add your user to have read and write access in the sharing and permissions section

Use sudo -i to switch to $root, then execute npm install -g xxxx

Reinstall node and npm with Node Version Manger (as per written in npm documentation) to avoid permission errors:

In OSX:

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.8/install.sh | bash

or follow this article:

http://dev.topheman.com/install-nvm-with-homebrew-to-use-multiple-versions-of-node-and-iojs-easily/

Windows users should install nvm-windows. For further help how to install nvm refer the nvm readme.

Then choose for example:

nvm install 8.0.0
nvm use 8.0

Now you can give another try:

npm install -g less