This is in follow up to my question in qnx4.devtools. I posted it in the
wrong place, my applogies…
I think I found why I’m having problems.
pdebug opens /dev/ptyp0 to feed data into and read data from my program. It
then spawns program and attaches stdin, stdout and stderr of my program to
/dev/ttyp0. I confirmed this with ‘sin fds’.
The problem I think is that data written to /dev/ptyp0 is not coming out of
(as input into my program) /dev/ttyp0.
I did two tests:
- pterm -d /dev/ptyqf &
pterm -d /dev/ttyqf &
Two pterms started…if I typed in the pterm attached to ttyqf…the
characters typed appeared in the pterm attached to /dev/ptyqf
BUT if I typed in the pterm attached to /dev/ptyqf, the characters appeared
in itself, while nothing appeared in pterm attached to /dev/ttyqf.
So after having a converstation with cdm, he mentioned that this would not
work…so…I tried just cat and echo.
Thus test #2:
I had the same response with an interesting twist. ‘cat’ would
block…waiting for data if attached to /dev/ptyqf (i.e. ‘cat /dev/ptyqf’),
but would exit instantly if attached to /dev/ttyqf. (i.e. ‘cat /dev/ttyqf’)
If ‘cat’ was attached to /dev/ptyqf and I did 'echo “testing”
/dev/ttyqf’…cat would spit out the text “testing” and continue to wait
for more data.
I couldn’t get any data out of /dev/ttyqf using cat. (I also tried ‘cat <
/dev/ttyqf’…same thing…would just return to the shell prompt. But if I
‘cat </dev/ptyqf’ it would block, waiting for data).
So…noticing that stdin of my program is attached to /dev/ttyp0, I have
come to the conclusion that this relationship is behaving just like my pterm
and cat/echo tests. Thus pdebug is sending data faithfully, but it is never
getting through /dev/ttyp0 as stdin to my program.
Two things: Am I coming to the correct conclusions? Second…can someone
point me to a reference that I may come to a more accurate definition of the
pseudo terminal? I think I have a too simplistic view of it all.
I am going to assume that this is correct behavior of devc-pty, and thus I
am never going to get input into my remote-debuged program unless I write my
own version of devc-pty that is simply just a bi-directional fifo pipe on
BTW: I’m not complaining…just trying to understand what I’m dealing