Dockerfile: Setting multiple environment variables in single line : <p>I was under the impression that environmental variables could be set on a single line as follows so as to minimize intermediary images.</p>

<pre><code>FROM alpine:3.6
ENV RUBY_MAJOR 2.4 \
    RUBY_VERSION 2.4.1 \
    RUBY_DOWNLOAD_SHA256 4fc8a9992de3e90191de369270ea4b6c1b171b7941743614cc50822ddc1fe654 \
    RUBYGEMS_VERSION 2.6.12 \
    BUNDLER_VERSION 1.15.3
</code></pre>

<p>However, running a container based off of this snippet and calling <code># set |grep RU</code> I see that the variables are not being assigned separately, but are combined into a single string.</p>

<pre><code>RUBY_MAJOR='2.4     RUBY_VERSION 2.4.1     RUBY_DOWNLOAD_SHA256 4fc8a9992de3e90191de369270ea4b6c1b171b7941743614cc50822ddc1fe654     RUBYGEMS_VERSION 2.6.12     BUNDLER_VERSION 1.15.3'
</code></pre>

<p>However, if I explicitly set each variable as below, I get the expected output and there are no errors when calling the variables. </p>

<pre><code>ENV RUBY_MAJOR 2.4
ENV RUBY_VERSION 2.4.1
ENV RUBY_DOWNLOAD_SHA256 4fc8a9992de3e90191de369270ea4b6c1b171b7941743614cc50822ddc1fe654
ENV RUBYGEMS_VERSION 2.6.12
ENV BUNDLER_VERSION 1.15.3
</code></pre>

<p><strong>Question:</strong> Is  it is possible to combine the setting of environment variables on a single line? If so, how would I do it? And is it a good practice?</p>
