other ubuntu version in docker

(as root)

docker run -ti ubuntu:latest /bin/bash

(-ti is interactive)

apt-get and do your stuff.

any change is deleted on exit. 

To save the changes 

get the container id by

docker container ls

then

docker commit <container id> name

to change the startup command you can create a Dockerfile reading

# Use an official Python runtime as a parent image

FROM cubuntu

# Set the working directory to /app

WORKDIR /home/fabio

# Copy the current directory contents into the container at /app

COPY startup.sh /

ENTRYPOINT ["/startup.sh"]

where startup.sh is a script in the same file of the Dockerfile

To mount filesystems of the host (e.g. to use X.In this case,create the user)

docker run --hostname beaver -ti -v /tmp/.X11-unix:/tmp/.X11-unix -v /home/fabio:/home/fabio beaver

sources:

http://fabiorehm.com/blog/2014/09/11/running-gui-apps-with-docker/

https://www.techrepublic.com/article/how-to-commit-changes-to-a-docker-image/

https://forums.docker.com/t/is-it-possible-to-pass-arguments-in-dockerfile/14488/3

https://docs.docker.com/storage/bind-mounts/#choosing-the--v-or---mount-flag

https://stackoverflow.com/questions/43031100/when-to-use-hostname-in-docker