yes "$(seq 231 -1 16)" | while read i; do printf "\x1b[48;5;${i}mHi $USER\n"; sleep .02; done
docker run -it ubuntu /bin/bash
http://www.projectatomic.io/blog/2016/01/how-to-run-a-more-s...
http://www.projectatomic.io/blog/2014/09/yet-another-reason-...
In newer docker, the defaults are really good, but even then, it is worth reading up.