printf goes to serial port?

Matt Wozniski
Fri Dec 19 19:35:00 GMT 2008

On Fri, Dec 19, 2008 at 2:30 PM, Gary R. Van Sickle wrote:
>> From: Alex Martin
>> Hello,
>> I have a cygwin environment, running some software I am
>> writing to talk to some serial devices.
>> Somehow, trying to debug why I could not see printf output to
>> console, I ran a serial port sniffer and voila all of my
>> printf commands are writing on the serial port.
> I can't say that it would cross my mind to look for my missing printf output
> on a serial port, even if I was using a serial port in other parts of the
> program to talk to something.  Whatever it was that gave you the hunch to do
> that is probably at the core of your problem.

My slightly wild guess is that you do an open() on the serial device
without a controlling terminal and without passing the O_NOCTTY flag,
causing the serial device to become your controlling terminal.


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