How do I set an environment variable?

Question

In bash I can see npm environment variables with npm run env. USER=brianmackey is one such environment variable. How can I set an environment variable, say USER=billybob?

I know I can use npm config set <key> <value> [--global]. Is key+value always/in any case an environment variable? Can I set the environment variables in session?

Answer 1

Single Command

If you want to set environment variables for a single node command, you can simply do this:

$ USER=billybob node server.js

Loaded for each session

If you want to permanently set that environment variable for your user, edit your ~/.bash_profile and add the following line:

export USER="billybob"

This will automatically set the given environment variable each time you create a new terminal session.

Existing for the entire current session

Lastly, if you want to set the environment variable only for the current session, just run it as it's own command:

$ USER=billybob
$ node app.js # user is billybob
$ node app.js # user is still billybob

When you exit the session, these temporarily set environment variables will be cleared.