scratch

create scratch image

tar cv --files-from /dev/null | docker import - seanly/scratch

output to host

docker image save seanly/scratch:docker | tar --extract --wildcards --to-stdout '*/layer.tar' | tar --extract --ignore-zeros docker.tar.gz

or

docker save seanly/scratch:docker | gzip > images.tar.gz
gunzip -c images.tar.gz | tar --extract --wildcards --to-stdout '*/layer.tar' | tar --extract --ignore-zeros docker.tar.gz