Most of them. Mainly on purpose, (.env files) but many also accidentally. (shell history with tokens in the commands)
I recommend Envie: https://github.com/ilmari-h/envie
It's more convenient than having a bunch of .env.prod, .env.staging files laying around, not to mention more secure.
Most of them. Mainly on purpose, (.env files) but many also accidentally. (shell history with tokens in the commands)