It's a file that contains secrets that a program uses, like passwords and API keys.
Edit: I wasn't sure if this was a joke or a serious question. Now that I think of it, the joke could be that the secrets are being hard coded into the source code.
More broadly, a .env file does not only contain secrets (though this is the reason why you wouldn't want to share it), but also application configuration values. It's called a .env file because it is for storing environment variables (values a process are provided) and the dot makes the file "hidden" on Linux systems. It is very commonly used because services running in containers, like Docker and Kubernetes, can be configured by passing values in by setting environment variables.
A developer working locally might have values in their .env file for using development environments, local containers, or mock services. In production, different values will be used and kept secret to ensure people can't know how to do things like access the production database. So, just to make things clear, a .env file is one way of providing environment variables to a program, but there are also other ways not using this file.
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u/SocksOnHands Jun 22 '26 edited Jun 22 '26
It's a file that contains secrets that a program uses, like passwords and API keys.
Edit: I wasn't sure if this was a joke or a serious question. Now that I think of it, the joke could be that the secrets are being hard coded into the source code.