daemonize

void daemonize() {
    pid_t pid = fork();
    if (pid < 0) exit(EXIT_FAILURE);
    if (pid > 0) exit(EXIT_SUCCESS); // 부모 종료

    if (setsid() < 0) exit(EXIT_FAILURE);

    signal(SIGCHLD, SIG_IGN);
    signal(SIGHUP, SIG_IGN);

    pid = fork();
    if (pid < 0) exit(EXIT_FAILURE);
    if (pid > 0) exit(EXIT_SUCCESS); // 첫 번째 자식 종료

    umask(0);
    chdir("/");

    close(STDIN_FILENO);
    close(STDOUT_FILENO);
    close(STDERR_FILENO);
}