Linux isn't the only widely supported unix. FrreBSD , NetBSD have their adherents. Solaris is pretty widely used just not among consumers / desktops. Then you have Mac OS X which isn't exactly unix but is unix-like in many aspects (has a bash shell, you can use vi or emacs and of course perl). I would suspect more Mac desktops than Linux. Servers on Mac exist but relatively rare.
Finally, Perl runs on Windows. There are a number of Windows-specific Perl modules. Dana Hudes
