如何进入活动docker集装箱?

我已经进入生产箱,在那里我的docker集装箱在哪里,并能够列出他们与docker ps
我得到了一个容器列表,如下所示:

 CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 123456789012 postgres:9.5 "docker-entrypoint..." 6 minutes ago Up 6 minutes 1234/tcp post rails1234567 rails_image "/usr/bin/docker-e..." 23 hours ago Up 23 hours 0.0.0.0:4000/tcp rails_auto 

我试图进入rails_image使用命令:
docker exec -it rails_image bash
docker exec -it rails_auto bash
docker exec -it rails1234567 bash

他们失败,错​​误:
rpc error: code = 2 desc = oci runtime error: exec failed: container_linux.go:247: starting container process caused "exec: \"bash\": executable file not found in $PATH"

问题是bash没有安装在docker容器中。
正确的命令是:

docker exec -it rails1234567 sh

这是因为sh被安装在容器中。