You should be able to call Node.js by executing
nodejs (if that's not working it's
node, but I think default is
nodejs, can't check now).
To check version if you want:
To check where is it installed,
which will help you. It'll return where binary is located:
You can put code anywhere where you want. Then you start it with:
As this is working until you close session, you probably want to setup pm2 or forever. It'll help you to run node apps as a service.
DigitalOcean has great tutorial on this topic, covering everything you'll need - How To Set Up a Node.js Application for Production on Ubuntu 16.04.