コンテナIDを確認する

$ docker ps -a
CONTAINER ID        IMAGE                             COMMAND                  CREATED             STATUS                     PORTS                     NAMES
f61dccc8a165        redis:3.2.4                       "docker-entrypoint..."   10 minutes ago      Up 9 minutes               0.0.0.0:6379->6379/tcp    devserverdocker_cache_1
fdcc61821a48        mysql:5.6                         "docker-entrypoint..."   10 minutes ago      Up 9 minutes               0.0.0.0:3306->3306/tcp    devserverdocker_db_1
a7378ae08afc        deangiberson/aws-dynamodb-local   "/usr/bin/java -Dj..."   10 minutes ago      Up 9 minutes               0.0.0.0:8000->8000/tcp    devserverdocker_dynamo_1

コンテナに入る

$ docker exec -it fdcc61821a48 /bin/bash
root@fdcc61821a48:/#
root@fdcc61821a48:/# exit

※ docker exec -it だと docker attach と違って、exitしてもコンテナは終了しない