I would guess that a fair number of Linux distros don't ship with a Ruby interpreter installed. (It would obviously be trivial to install one using apt-get or y

I would guess that a fair number of Linux distros don't ship with a Ruby interpreter installed. (It would obviously be trivial to install one using apt-get or yum or whatever, but it's not already installed.) Perl is there because it's long been considered a kind of extended shell-scripting language. Python's probably in most places because so many GTK/Gnome apps depend on it. But I'm not sure if Ruby is (yet) part of standard builds.