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

[Rony G. F. <Ron...@wu...>]

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