Why ruby?

There were two choices considered for the build system. Gjallar and Ruby. Gjallar has many facilities that a build system could make use of, logging, task scheduling, etc. At the time of writing Gjallar was not fully running on linux.

Ruby is closer to the metal than squeak, the metal being the OS, and its filing system, in particular the command-line that launches squeak itself. Ruby has an io class 'Rio' which makes dealing with either local files or remote entities really easy.

Ruby was chosen, satisfying the "Do the simplest thing that could possibly work" principle.