# File src/ruby_supportlib/phusion_passenger/platform_info/apache.rb, line 204
    def self.httpd_default_config_file(options = nil)
      if options
        info = apache2ctl_V(options)
      else
        info = apache2ctl_V
      end
      if info
        info =~ /-D SERVER_CONFIG_FILE="(.+)"$/
        filename = $1
        if filename =~ /\A\//
          return filename
        else
          # Not an absolute path. Infer from default root.
          if root = httpd_default_root(options)
            return "#{root}/#{filename}"
          else
            return nil
          end
        end
      else
        return nil
      end
    end