/bin/bash is on literally every machine I ever touch. It is on every Debian machine. It is on every Ubuntu machine. It is on every OS X machine. It is on every Windows (!) machine. And there are plenty of operations that are significantly more cumbersome to write in Ruby--otherwise, sure, I would do so. Backticks are nice, but there's no `set -e` (that I am aware of) and it becomes a huge hassle to do things in a smart, error-checking way.

So you have a chef recipe to download and compile the same version of bash on every platform you use?

How do you handle situations where bash is included by default?

Do you remove the package or just push your binary over the top?

If you don't remove it, what happens when a package update then replaces your binary?

How often do you update the recipe to make sure it's getting the latest stable version and applying security patches?