# File src/ruby_supportlib/phusion_passenger/platform_info/apache.rb, line 358
    def self.httpd_mods_available_directory(options = nil)
      config_file = httpd_default_config_file(options)
      return nil if !config_file

      # mods-available is supposed to be a Debian extension that only works
      # on the APT-installed Apache, so only return non-nil if we're
      # working against the APT-installed Apache.
      config_dir = File.dirname(config_file)
      if config_dir == "/etc/httpd" || config_dir == "/etc/apache2"
        if File.exist?("#{config_dir}/mods-available") &&
           File.exist?("#{config_dir}/mods-enabled")
          return "#{config_dir}/mods-available"
        else
          return nil
        end
      else
        return nil
      end
    end