Evaluating container environment variables in Dockerfile commands


Docker in Linux environments knows to evaluate environment variables in Dockerfile commands like ENV or ENTRYPOINT. For example, the following command line in Dockerfile that generates linux platform container image is perfectly legal:

ENV PATH $PATH:/usr/bin/myapp

However, it is impossible to write such line for Windows platform container. In case of Windows the resulted value of the PATH variable for the line

ENV PATH %PATH%;c:\myapp

will be %PATH%;c:\myapp

Does anyone know how to achieve the functionality when docker evaluates the environment variables in the context of the container?
And for which commands of the Dockerfile it is possible to do?

Thank you,

Check out the reference to =$env:variable_name