How to use the log.file function in log

let port;

  if (!addArgs['server.endpoint']) {
    port = findFreePort(options.maxPort);
    endpoint = protocol + '://127.0.0.1:' + port;
  } else {
    endpoint = addArgs['server.endpoint'];
    port = endpoint.split(':').pop();
  }

  let instanceInfo = {
  role, port, endpoint, rootDir};

  args['server.endpoint'] = endpoint;
  args['database.directory'] = dataDir;
  args['log.file'] = fs.join(rootDir, 'log');

  if (options.verbose) {
    args['log.level'] = 'info';
  } else {
    args['log.level'] = 'error';
  }

  // flush log messages directly and not asynchronously
  // (helps debugging)  
  args['log.force-direct'] = 'true';

  if (protocol === 'ssl') {
    args['ssl.keyfile'] = fs.join('UnitTests', 'server.pem');
  }

  args = Object.assign(args, options.extraArgs);

}, true, function(e) {
		// Update log event toggle.
		$('#logging-events').val((e['log.event'] === 'true' ? 'Yes' : 'No'));
		// Update log error toggle.
		$('#logging-errors').val((e['log.error'] === 'true' ? 'Yes' : 'No'));
		// Update log chat toggle.
		$('#logging-chat').val((e['log.file'] === 'true' ? 'Yes' : 'No'));
		// Update log keep days.
		$('#log-days').val(e.log_rotate_days);
		// Set mute mode.
		$('#bot-mute-mode').val((e['response_@chat'] === 'true' ? 'No' : 'Yes'));
		// Set action mode.
		$('#bot-action-mode').val((e['response_action'] === 'true' ? 'Yes' : 'No'));
		// Set whisper mode.
		$('#bot-whisper-mode').val((e['whisperMode'] === 'true' ? 'Yes' : 'No'));
	});
});

gameTitle = msgObject['results']['game'];
                if (gameTitle === undefined || gameTitle === null) {
                    gameTitle = "Some Game";
                }

                $('#gameTitleInput').val(gameTitle);
                sendDBQuery("dashboard_deathctr", "deaths", gameTitle);
            }

            if (panelCheckQuery(msgObject, 'dashboard_loggingModeEvent')) {
                loggingModeEvent = msgObject['results']['log.event'];
                $("#logEvent").html(modeIcon[loggingModeEvent]);
            }

            if (panelCheckQuery(msgObject, 'dashboard_loggingModeFile')) {
                loggingModeFile = msgObject['results']['log.file'];
                $("#logFile").html(modeIcon[loggingModeFile]);
            }

            if (panelCheckQuery(msgObject, 'dashboard_loggingModeErr')) {
                loggingModeError = msgObject['results']['log.error'];
                $("#logError").html(modeIcon[loggingModeError]);
            }

            if (panelCheckQuery(msgObject, 'dashboard_deathctr')) {
                amount = msgObject['results'][gameTitle];
                if (gameTitle == null || amount == null) {
                    $("#deathCounterValue").html('0');
                    return;
                }
                $("#deathCounterValue").html(msgObject['results'][gameTitle]);
            }