Docker containers are a bit like virtual machines sometimes. Namely, you can connect to a container and run shell scripts there. 

the command for it is:

__docker exec -it container-name bash__

**-it** - this is very important! this means interactive terminal: your terminal becomes the containers' terminal.

**bash** is your UNIX shell. most minimal images include .sh, some more equipped ones also have bash. The advantage of bash over sh is: command history, better scripting, tab completion