NPM Packages (with CLI) installed globally return command not found

Question

I've had this happen twice to me before. The first time I assumed it was an error with NPM, so I uninstalled Node & NPM and didn't use the package that was giving me an error. I did a fresh install & began working on another project. I'd installed the package (and the version of it with cli). The command line command worked during the terminal session during which i'd installed it both globally and in my project. However in other terminal tabs and in new terminal sessions the command returns command not found. when I run npm root i receive: /Users/MYUSERNAME/node_modules

and when I run npm root -g, i receive:

/Users/MYUSERNAME/.npm-global/lib/node_modules

For what it's worth the two packages I've tried this with are mjml (and mjml-cli) and gulp (and gulp-cli). I've uninstalled both and reinstalled again from my root directory using the -g flag and that doesn't seem to have changed anything.

Answer 1

I appear to have missed this somewhere in the googling I did before asking this question. Apparently I had been accidentally installing global packages in my local folder (/Users/YOURUSERNAME/node_modules).

Running npm config set prefix /usr/local fixed the issue.