TIOCNMODEM/tty/VS2000

[R. J. Auletta]

We have a VS2000 (Ultrix 3.1) which boots 
requiring modem signals on tty02. Since we wish
to use the serial port as a printer port we
have getty disabled and have run the following program.
(Which should permanently disable modem control.)
But when the system reboots, the port once again
requires modem signals to avoid having writes block.

Any suggestions? What's missing? Is this ioctl broken?

-R  J Auletta


#include <sys/ioctl.h>

main()
{
int fd;

int turnoff = 1;
int error = 0;

fd = open("/dev/tty02",O_NDELAY | O_RDWR);
error = ioctl(fd, TIOCNMODEM, &turnoff);

fd = open("/dev/tty03",O_NDELAY | O_RDWR);
error = ioctl(fd, TIOCNMODEM, &turnoff);
}