#include <comedilib.h>
int comedi_fileno (comedi_t * device);
The function comedi_fileno returns the integer descriptor for the device dev. This descriptor can then be used as the file descriptor parameter of read(), write(), etc. This function is intended to mimic the standard C library function fileno(). If dev is an invalid comedi_t pointer, the function returns -1 and sets the appropriate Comedilib error value.