docker bash 에서 env 변수를 에코하는 방법
docker exec <container-name> env
dockerfile VAR
ENV abc=hello
ENV abc=bye def=$abc
ENV ghi=$abc
dockerfile env variabes
FROM busybox
ENV foo /bar
WORKDIR ${foo} # WORKDIR /bar
ADD . $foo # ADD . /bar
COPY \$foo /quux # COPY $foo /quux