Fd = open("/dev/ttyUSB0", O_RDONLY | O_NOCTTY);
if (Fd == -1) {
    printf("Could not open serial port: %sn", strerror(errno));
    return 1;
}

fcntl(Fd, F_SETFL, 0);

char buf;
while (1) {
    read(Fd, &buf, 1);
    printf("%c", buf);
}

void signal_callback_handler(int signum) {
    printf("Caught SIGTERMn");
    close(Fd);
    exit(signum);
}

signal(SIGINT, signal_callback_handler);

Boot.
^CTo send: Caught SIGTERM

struct termios port_settings;          // structure to store the port settings in
cfsetispeed(&port_settings, B115200);  // set baud rates
cfsetospeed(&port_settings, B115200);
port_settings.c_cflag &= ~PARENB;      // set no parity, stop bits, data bits
port_settings.c_cflag &= ~CSTOPB;
port_settings.c_cflag &= ~CSIZE;
port_settings.c_cflag |= CS8;
tcsetattr(Fd, TCSANOW, &port_settings);// apply the settings to the port