Laravel 5.7 - How to set all variables inside .env to point to test environment when the system is started?

I have 2 buckets prod and dev. Inside .env I have S3_PROD and S3_DEV. I want my system to point to S3_DEV when I am in my dev environment.

Taking consideration that I could have 10 variables to be pointed to a specific endpoint based on our environment what should be the best approach to set that?

via Chebli Mohamed