Invoke an octave session via pipe

[Qianqian Fang]

thank you John, and also Michael's reply for using the -i option.

I tried -i and my initial pipe read returned the "octave:1>" prompt,
however, sending commands via my pascal function still
failed to give me any more output to read.

I am not sure I understood the the experiment outlined in your reply.
I ran the "octave --interactive < fifo > foo.out " command and it simply
gave an empty foo.out file; I did not have chance to run the cat command
from another term and octave already quit.

In the past, I only got succeed using pipes to run a .m file from
command line and retrieve the printed results, but that was a
single execution; but now what I am trying to achieve is to interact
with an persistent session (sort of like a GUI), I am not sure if this
is indeed possible with pipe operations.

I also found some possible issues on the pascal side, I posted it
on the Lazarus forum and I will let you know if I get any useful
feedback from there.

Qianqian


John W. Eaton wrote:
> On  7-May-2009, Qianqian Fang wrote:
>
> | What makes me curious is why my stdout reading did not give me the
> | octave prompt, i.e. "octave:1>"? looks like once octave get started,
> | it will start something else, which I can not access its stdout via
> | octave's stdout.
>
> No, I think Octave writes the prompt and most output to stdout.
> Probably you want to use the --interactive option when talking to
> Octave over a pipe.  If you are on a Unixy system, try this
> experiment:
>
>   in one terminal window, run
>
>     mkdir fifo
>     octave --interactive < fifo > foo.out
>
>   and in another, type
>
>     cat > fifo
>     svd (rand (3))
>     fprintf (stderr, "stderr!\n")
>
> and then look at foo.out.  It should contain all of Octave's output
> except the "stderr!" message, which should have been printed to the
> terminal where you started Octave.
>
> jwe
>
>