# Environment variables in k6
[Documentation](https://k6.io/docs/using-k6/environment-variables/)
In [[k6 (tool)|k6]], you can use environment variables to pass parameters at runtime.
Within the script, use literals:
```js
http.get('http://${__ENV.DOMAIN}');
```
When running the script, set values like this:
```shell
k6 run -e DOMAIN=nicolevanderhoeven.com script.js
```