serial ports linux c++

With recent Linux kernels, there will be the directory /dev/serial containing links to the serial devices. This contains only links to existing devices.

Classic serial ports are linked as /dev/ttySx and USB to serial adapters are linked as /dev/ttyUSBx where x is enumerating the ports starting at zero.

Especially the /dev/ttySx links may be also present for not existing ports. So these must be checked. This can be done on the command line using

setserial -g /dev/ttySx

To check the existance programmatically, open the device and issue an ioctl TIOCGSERIAL request:

int fd = open(device, O_RDWR | O_NONBLOCK);
if (fd != -1)
{
    serial_struct info;
    // Port exists when this returns zero
    ioctl(fd, TIOCGSERIAL, &info);
    close(fd);
}