testdata/Dockerfile|1 col 1| Always tag the version of an image explicitly
testdata/Dockerfile|3 col 1| Avoid additional packages by specifying --no-install-recommends
testdata/Dockerfile|3 col 1| Pin versions in apt get install. Instead of apt-get install <package> use apt-get install <package>=<version>
testdata/Dockerfile|5 col 1| Multiple consecutive RUN instructions. Consider consolidation.
testdata/Dockerfile|5 col 1| Remove space after = if trying to assign a value (for empty string, use var='' ... ).
testdata/Dockerfile|6 col 1| Use WORKDIR to switch to a directory
testdata/sub-dir/Dockerfile|1 col 1| Always tag the version of an image explicitly
testdata/sub-dir/Dockerfile|3 col 1| Use WORKDIR to switch to a directory