While using NVM on Linux, it loads Node.js and NPM from .bashrc in the home directory of your user. However, if you execute the command with sudo like sudo npm start it will result in sudo: npm: command not found since .bashrc of root is not managed by NVM.
Managing Node.js versions on Linux is no longer a pain in the ass with NVM (Node Version Manager). It can install different versions of Node.js and NPM on a single machine, switch versions anytime you wish. And the best part is NVM is just a Bash script, truly a lightweight helper for both testing and production.