$ curl https://get.docker.com/ | sh
$ sudo sh -c 'usermod -a -G docker $SUDO_USER'
再ログイン
$ sudo fallocate -l 4G /swap
$ sudo chmod 600 /swap
$ sudo mkswap /swap
$ sudo swapon /swap
$ mkdir docker-app
$ cd docker-app
$ cat > builds1.sh << 'EOS'
mkdir node
cd node
wget https://raw.githubusercontent.com/nodejs/docker-node/72dd945d29dee5afa73956ebc971bf3a472442f7/8/alpine/Dockerfile
docker build -t mamemomonga/rpi-node:8.11.3-alpine .
cd ..
mkdir ruby
cd ruby
wget https://raw.githubusercontent.com/docker-library/ruby/c43fef8a60cea31eb9e7d960a076d633cb62ba8d/2.4/alpine3.6/Dockerfile
docker build -t mamemomonga/rpi-ruby:2.4.4-alpine3.6 .
cd ..
EOS
$ nohup bash builds1.sh &
$ tail -f nohup.out
寝る