return fmt.Sprintf("%s-%s.log", ctx.String("log-prefix"), fmt.Sprintf("%X", time.Now().UTC().UnixNano()))
		}
	}

	output, err := logger.NewDir(logger.Options{
		Directory:       lgDirAbs,
		MaximumFileSize: int64(lgSize),
		Compress:        ctx.Bool("log-compress"),
		FileNameFunc:    fileNameFunc,
	})
	if err != nil {
		return nil, err
	}
	logger.EnableJSON()
	return output, nil
}