Node.js - how to set environment variables in code

javascript linux node.js bluetooth-lowenergy
Alex picture Alex · Apr 10, 2015 · Viewed 23.1k times · Source

I am fairly new to node.js, and have a program that I have to set an environment variable in order to run (using the noble library, my bash command is: sudo NOBLE_HCI_DEVICE_ID=x node program.js, to tell my code which Bluetooth adapter - HCI device - to use).

The reason behind this is that I have a number of modules, each needing their own Bluetooth adapter, and I wish to specify in my code which adapter each module should use.

I've found lots of articles telling me how to consume environment variables in my code and set them via the command line (process.env.VARIABLE_NAME), but nothing telling me how to set them from within node.js.

Is it possible to set the environment variables in my node.js code?

Answer

M. Adam Kendall picture M. Adam Kendall · Apr 10, 2015

You can not only consume environment variables in node with process.env but also set them. This will set the variable within your current node process and any child processes it calls, but not the calling shell itself.

// consume
var alreadySetEnvVarForDevice = process.env.NOBLE_HCI_DEVICE_ID

// set
process.env['NOBLE_HCI_DEVICE_ID'] = 1

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