env in dockerfile code example

Example 1: dockerfile env

ENV abc=hello
ENV abc=bye def=$abc
ENV ghi=$abc

Example 2: docker ARG

$ docker build --build-arg some_variable_name=a_value

Example 3: dockerfile env variabes

FROM busybox
ENV foo /bar
WORKDIR ${foo}   # WORKDIR /bar
ADD . $foo       # ADD . /bar
COPY \$foo /quux # COPY $foo /quux