if sourceEndpoint == "" {
		log.Fatalln("source Endpoint is not provided")
	}

	if sourceAccessKey == "" {
		log.Fatalln("source Access key is not provided")
	}

	if sourceSecretKey == "" {
		log.Fatalln("source Secret key is not provided")
	}

	if sourceBucket == "" && sourcePrefix != "" {
		log.Fatalln("--source-prefix is specified without --source-bucket.")
	}

	if targetEndpoint == "" {