Get Environment Variable from Docker Container

Question

What\'s the simplest way to get an environment variable from a docker container that has not been declared in the Dockerfile?

For instance, an environment v

Answer 1

We can modify entrypoint of a non-running container with the docker run command.

Example show PATH environment variable:

1. using bash and echo: This answer claims that echo will not produce any output, which is incorrect.

   docker run --rm --entrypoint bash  -c 'echo "$PATH"'
   

2. using printenv

   docker run --rm --entrypoint printenv  PATH