Re: [netrexx-pipelines] Strangeness when filtering linux stty output

[J L. T. <jlt...@ma...>]

On 2023-08-04 06:14:27 Rony G. Flatscher wrote:
> On 04.08.2023 06:30, J Leslie Turriff wrote:
> > On 2023-08-02 06:45:16 Rony G. Flatscher wrote:
> >> On 31.07.2023 16:27, Marc Remes wrote:
> >>> pipe 'command stty --all|console also runs fine.. Its output is empty
> >>> because it is not connected to a real/pseudo terminal, as echo dog |tty
> >>> reports.
> >>>
> >>> Indeed, we're not doing bash redirection, it is now java that is doing
> >>> the redirection. The command stage starts the stty process by r.exec
> >>> and connects to its stdin. For the stty process there's no difference
> >>> whether the redirection is done by bash or java, in both cases its
> >>> stdin is not a terminal. And thus stty has no effect.
> >>
> >> According to the JavaDocs for Process
> >> <https://docs.oracle.com/javase/8/docs/api/java/lang/Process.html>  "...
> >> By default, the created subprocess does not have its own terminal or
> >> console. ..." so this may be an explanation that stty would not find it
> >> and what Marc tries to point out. Not sure about ProcessBuilder
> >> <https://docs.oracle.com/javase/8/docs/api/java/lang/ProcessBuilder.html
> >>> can be used instead and making a difference?
> >>
> >> Maybe doing something like "stty -F `tty` --all" would work and if not
> >
> > supplying explicitly the device path, if known?
> > 	You're a genius!  It took several tries, and one has to know of a valid
> > tty to plug into the command, but yes, that's the key.
> >
> > 	I tried these in the jEdit console:
> > | ~> stty -F 'tty' --all
> >
> > as you suggested, but stty seems to want to set tty attributes when it
> > sees -F; so I tried
> >
> > | ~> stty --all -F 'tty'
> >
> > but it said "stty: tty: No such file or directory" so I ran the w command
> > to find a "real" tty, and it seems like /dev/pts/## (where ## is any of
> > the ttys defined to the system) works, and the output from --all is not
> > written to that device, but to the console where stty was invoked! so we
> > see something like the attached output.  The tty must belong to the
> > account invoking stty or we get "Permission denied".
> >
> > 	Thank you!  Thank you!
>
> You are very welcome, glad that I could help a little bit.
>
> One more remark: have you tried the back-ticks ` around "tty"?
>
> E.g. in your example (that did not work) you write:
>
>     stty --all -F 'tty'
>
> If you write it this way, would it work for you?
>
>     echo `tty`
>     stty --all -F `tty`
>
> ---rony

	I had not tried that before, but I just did and it fails when issued from the
jEdit console.  See the attached snapshot.

	I'm fairly happy with what I have that is working; now I just have to get my
nrx pipeline program that uses it to work.  It seems that mixing the address
and the pipe commands in a simple pipeline program (stty-rows.njp, also
attached) makes the pipe compiler choke; so using nrx pipelines to simplify
what my bash version does might require an even longer NetRexx program. :-(

Leslie