Sometimes you want packages that exist outside of the language-specific packaging
ecosystems of Python/R/Julia. Binder makes it possible to apt-install packages
from the ubuntu apt repository. This repository demonstrates how to do this by specifying
names in an apt.txt file.
The apt.txt file should list all packages that your notebooks
depend on, and they will be installed using:
apt-get install --yes --no-install-recommends
The base Binder image contains no extra dependencies, so be as explicit as possible in defining the packages that you need.
In this example we include the tools cowsay and lolcat which will be installed in
the environment, and our notebook uses them to show a colorful message.