public static void main(String[] args) {
        try {
            Options options = getOptions();

            CommandLineParser cliParser = new DefaultParser();

            CommandLine line = cliParser.parse(options, args);
            if (line.hasOption("help")) {
                usage(options);
            }
            TikaServerConfig tikaServerConfig = TikaServerConfig.load(line);
            PREVENT_STOP = tikaServerConfig.isPreventStopMethod();

            execute(tikaServerConfig);
        } catch (Exception e) {
            LOG.error("Can't start: ", e);
            System.exit(-1);
        }
    }
This value is set to the server's id in the forked process.
tika-server/tika-server-core/src/main/java/org/apache/tika/server/core/TikaServerCli.java