alias dockerfile='script.sh'


script.sh:

#!/bin/bash
echo "FROM scratch"
docker history --no-trunc $@  | tac | tr -s ' ' | cut -d " " -f 5- | sed 's,^/bin/sh -c #(nop) ,,g' | sed 's,^/bin/sh -c,RUN,g' | sed 's, && , \\\n  & ,g' | sed 's,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g' | head -n -1


Example usage for Docker Hub image:
$ dockerfile myusername/myimage:latest