isatty()                 Check for Character Device
 
 #include   <io.h>
 
 int        isatty(handle);
 int        handle;                      Handle of the device being tested
 
    isatty() checks whether 'handle' is associated with a character
    device (i.e., a terminal, console, printer, or serial port).
 
    Returns:    Non-zero if 'handle' is associated with a device;
                otherwise zero.
 
  -------------------------------- Example ---------------------------------
 
    The following statements determine if 'fhndl' is associated with a
    character device. If not, they get the file pointer position.
 
          #include <io.h>
 
          int fhndl;
          long position;
 
          main()
          {
                fhndl = open("data",O_RDWR);
                if (isatty(fhndl) == 0)
                   position = tell(fhndl);
           }