# File lib/phusion_passenger/platform_info/apache.rb, line 86
        def self.httpd_version(options = nil)
                if options
                        httpd = options[:httpd] || self.httpd(options)
                else
                        httpd = self.httpd
                end
                if httpd
                        `#{httpd} -v` =~ %r{Apache/([\d\.]+)}
                        return $1
                else
                        return nil
                end
        end