Simple method to find host OS versioning in Ruby

getOS.rb

#!/usr/bin/env ruby

# Ruby code snippets to determine MacOS versioning with more to come

# Inspired by AJ Acevedo's Gist: https://gist.github.com/AJ-Acevedo/5421660

##############################################################
# RbConfig to determine host OS and exit if not mac or linux #
##############################################################

require 'rbconfig'

def getOSVersioning()
    os = RbConfig::CONFIG['host_os']
    if (os.include?"darwin")
        versionNo = os.split("darwin")
        versionNo = versionNo[1].to_f 
        if (versionNo > 15)
            os = "MacOS"
            case versionNo
            when 16
                versionName = "Sierra"
            when 17
                versionName = "High Sierra" 
            when 18
                versionName = "Mojave"    
            end    
        else 
            os = "OS X"
            case versionNo
            when 9
                versionName = "Leopard"
            when 10
                versionName = "Snow Leopard"
            when 11
                versionName = "Lion"
            when 12
                versionName = "Mountain Lion"
            when 10
                versionName = "Mavericks"
            when 11
                versionName = "Yosemite"
            when 12
                versionName = "El Capitan"
            end        
        end    
    elsif (os.include?"linux")
        versionNo = os.split("linux")
        os = "Linux"
    else
        versionNo = os.split("windows")
        os = "Windows"
    end
    return "#{os} #{versionNo} #{versionName}"
end


@os = getOSVersioning()
puts @os