Docker: update + remove old unused images

docker-update-prune.sh

#!/bin/bash

# for every named image
docker images | sed "1d" | cut -d " " -f1 | sort -n | uniq | grep -v '^<none>$' |
while read f ; do
 # pull latest image, skip pruning if can't pull
 if ! docker pull "$f" ; then continue ; fi
 # get latest image id
 IMAGE_ID=`docker images "$f" | sed "1d;2q" | sed 's/^[^ ]*  *[^ ]*  *//;s/ .*$//'`
 if [ "x$IMAGE_ID" == "x" ] ; then continue ; fi
 # remove all except latest and IMAGE_ID
 docker images "$f" | sed "1d" | grep -v " latest " | sed 's/^[^ ]*  *[^ ]*  *//;s/ .*$//' | sort | uniq | grep -v "$IMAGE_ID" |
 while read g ; do
  echo docker rmi $g
 done
done

# remove all "unnamed && unused"
docker images -a | grep '^<none>' | sed "s/^<none> *<none> *//;s/ .*//" | xargs -n1 docker rmi