# File src/ruby_supportlib/phusion_passenger/platform_info/apache.rb, line 275
    def self.httpd_actual_error_log(options = nil)
      if config_file = httpd_default_config_file(options)
        begin
          contents = File.open(config_file, "rb") { |f| f.read }
        rescue Errno::ENOENT
          log "#{config_file} does not exist"
          return nil
        rescue Errno::EACCES
          log "Unable to open #{config_file} for reading"
          return nil
        end
        # We don't want to match comments
        contents.gsub!(/^[ \t]*#.*/, '')
        if contents =~ /^[ \t]*ErrorLog[ \t]+(.+)[ \t]*$/i
          filename = unescape_apache_config_value($1, options)
          if filename && filename !~ /\A\//
            # Not an absolute path. Infer from root.
            if root = httpd_default_root(options)
              return "#{root}/#{filename}"
            else
              return nil
            end
          else
            return filename
          end
        elsif contents =~ /ErrorLog/i
          # The user apparently has ErrorLog set somewhere but
          # we can't parse it. The default error log location,
          # as reported by `apache2ctl -V`, may be wrong (it is on OS X).
          # So to be safe, let's assume that we don't know.
          log "Unable to parse ErrorLog directive in Apache configuration file"
          return nil
        else
          log "No ErrorLog directive in Apache configuration file"
          return httpd_default_error_log(options)
        end
      else
        return nil
      end
    end