mark (07/20/82)
Could someone who is familiar with the pty driver answer a question for me? I tried installing some ptys on my 4.1BSD system, and then used them by putting a getty on ttya and doing 'cu ttya'. It works fine for a minute or two, allowing me to get logged onto the pty and type a few commands. Then, suddenly cu thinks it lost the line. Turns out one of the reads on the controller end returned a -1, with errno set to ENXIO. ("No such device or address.") I couldn't see anything in the driver that could generate this. I changed cu to ignore the error condition and it seemed to work OK. What would cause a pty controller device to return a read error? What is the standard technique for programming around this - just ignore the error? This seems dangerous - perhaps only ENXIO's should be ignored. Anyone know what possible errors there might be? Reply to mark@Berkeley on the arpanet. Thanks much.