func createSystemdLogfile(service string, outputMode string, outputDir string) error {
	// Generate the journalctl command.
	journalCmdArgs := []string{fmt.Sprintf("--output=%v", outputMode), "-D", *journalPath}
	if service == "kern" {
		journalCmdArgs = append(journalCmdArgs, "-k")
	} else {
		journalCmdArgs = append(journalCmdArgs, "-u", fmt.Sprintf("%v.service", service))
	}
	cmd := exec.Command("journalctl", journalCmdArgs...)

	// Run the command and record the output to a file.
	output, err := cmd.Output()
	if err != nil {
		return fmt.Errorf("Journalctl command for '%v' service failed: %v", service, err)
	}
	logfile := filepath.Join(outputDir, service+".log")
	if err := ioutil.WriteFile(logfile, output, 0444); err != nil {
		return fmt.Errorf("Writing to file of journalctl logs for '%v' service failed: %v", service, err)
	}
	return nil
}
func createSystemdLogfile(service string, outputMode string, outputDir string) error {
	// Generate the journalctl command.
	journalCmdArgs := []string{fmt.Sprintf("--output=%v", outputMode), "-D", *journalPath}
	if service == "kern" {
		journalCmdArgs = append(journalCmdArgs, "-k")
	} else {
		journalCmdArgs = append(journalCmdArgs, "-u", fmt.Sprintf("%v.service", service))
	}
	cmd := exec.Command("journalctl", journalCmdArgs...)

	// Run the command and record the output to a file.
	output, err := cmd.Output()
	if err != nil {
		return fmt.Errorf("Journalctl command for '%v' service failed: %v", service, err)
	}
	logfile := filepath.Join(outputDir, service+".log")
	if err := ioutil.WriteFile(logfile, output, 0444); err != nil {
		return fmt.Errorf("Writing to file of journalctl logs for '%v' service failed: %v", service, err)
	}
	return nil
}
// Create logfile for systemd service in outputDir with the given journalctl outputMode.