final String filename = new String(Base64.getDecoder().decode(id), StandardCharsets.UTF_8).replace("..", "").replaceAll("\\s", "");
        final String logFilePath = systemHelper.getLogFilePath();
        if (StringUtil.isNotBlank(logFilePath) && isLogFilename(filename)) {
            final Path path = Paths.get(logFilePath, filename);
            return asStream(filename).contentTypeOctetStream().stream(out -> {

        final String filename = new String(Base64.getDecoder().decode(id), StandardCharsets.UTF_8).replace("..", "").replaceAll("\\s", "");
        final String logFilePath = systemHelper.getLogFilePath();
        if (StringUtil.isNotBlank(logFilePath) && isLogFilename(filename)) {
            final Path path = Paths.get(logFilePath, filename);
            return asStream(filename).contentTypeOctetStream().stream(out -> {

    public void test_getLogFilePath() {
        final File logFile = new File(systemHelper.getLogFilePath());
        assertEquals("logs", logFile.getName());
        assertEquals("target", logFile.getParentFile().getName());
        try {
            System.setProperty("fess.log.path", "logpath");
            assertEquals("logpath", systemHelper.getLogFilePath());
        } finally {
            System.clearProperty("fess.log.path");
        }

        buf.append("-Xlog:gc*,gc+age=trace,safepoint:file=");
        if (logFilePath != null) {
            buf.append(logFilePath);
        } else {
            buf.append(ComponentUtil.getSystemHelper().getLogFilePath());
        }
        buf.append(File.separator);
        buf.append("gc-").append(getExecuteType()).append(".log");
        buf.append(":utctime,pid,tags:filecount=5,filesize=64m");

            logger.warn("Failed to access system.properties.", e);
        }
    }

    protected void writeLogFiles(final ZipOutputStream zos, final String id) {
        final String logFilePath = systemHelper.getLogFilePath();
        if (StringUtil.isNotBlank(logFilePath)) {
            final Path logDirPath = Paths.get(logFilePath);
            try (Stream<Path> stream = Files.list(logDirPath)) {

        cmdList.add("-Dfess." + getExecuteType() + ".process=true");
        cmdList.add("-Dfess.log.path=" + (logFilePath != null ? logFilePath : systemHelper.getLogFilePath()));
        addSystemProperty(cmdList, "fess.log.name", getLogName("fess"), getLogName(StringUtil.EMPTY));
        if (logLevel == null) {
            addSystemProperty(cmdList, "fess.log.level", null, null);

        final Instant instant = Instant.ofEpochMilli(getCurrentTimeAsLong());
        return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
    }

    public String getLogFilePath() {
        final String value = System.getProperty("fess.log.path");
        if (value != null) {
            return value;
        }
        final String userDir = System.getProperty("user.dir");