Re: Redirecting stderr to stdout through pipe doesn't work the way it does in Linux

[David Karr <davidmichaelkarr at gmail dot com>]

On Wed, Dec 5, 2018 at 9:43 AM cyg Simple <cygsimple@gmail.com> wrote:

> On 12/5/2018 10:11 AM, David Karr wrote:
> > On Tue, Dec 4, 2018 at 12:52 PM Marco Atzeri <marco.atzeri@gmail.com>
> wrote:
> >
> >> Am 04.12.2018 um 21:41 schrieb David Karr:
> >>> "CYGWIN_NT-6.1 WACDTL03DK068X 2.9.0(0.318/5/3)"
> >>>
> >>> I installed a version of "kubectl" for windows, and I use it
> extensively
> >> in
> >>> Cygwin bash for scripting command-line automation. In general, this
> works
> >>> perfectly fine. I even use the same scripting in a Linux VM.
> >>>
> >>> I'm seeing an issue with one script that works fine in the Linux VM,
> but
> >>> not in Cygwin.
> >>>
> >>> The command line is approximately this:
> >>>
> >>>        kubectl exec pod -c container -i -t -- grep "string"
> >> stuff.properties
> >>> 2>&1 | sed -e 's/^propname=//'
> >>>
> >>> In Linux, this works perfectly fine.  In Cygwin, it says "stdout is
> not a
> >>> tty".
> >>>
> >>> I haven't updated my local Cygwin installation for quite a while. I'd
> >>> prefer not to, unless there is a strong chance this kind of thing would
> >> be
> >>> fixed.
> >>>
> >>
> >> as kubectl is not a Cygwin program, it is not aware of cygwin pty.
> >> You can try to use winpty to overcome the problem.
> >>
> >> https://github.com/rprichard/winpty
> >>
> >>
> >>
> > It turns out that not only had I already used winpty for similar
> > functionality, it was actually in place in the pipeline when I tried to
> do
> > this.  When I turned on debugging output, it showed that kubectl was
> > already being wrapped by winpty when it reported "stdout is not a tty".
> > However, this was one shell script wrapper deeper than I usually call it.
> > Does it matter whether winpty is called from the shell script I'm
> calling,
> > or from the script being called by the script I'm calling?
>
> Your query got me interested in looking and I believe that winpty needs
> to be at the front of all the commands so that it can communicate with
> mintty properly.  To overcome the need to remember you could add an
> alias to execute the command; `alias FOO="winpty FOO"'.
>

Sigh. What a mess. I can't get this to work.  It was easy enough when a
single script has to execute "kubectl", having "winpty" prefix that call,
but I'm trying to write a script that calls that other script, and even in
a pipeline.

If I have "winpty" prefix the call to the script that calls "kubectl", it
says:

    winpty: error: cannot start '...': Not found in PATH

When I changed it so it references the absolute path, it then says "%1 is
not a valid Win32 application. (error 0xc1)".  So, this makes it clear that
winpty can only directly execute Windows applications, which makes sense.

So how can I call a Windows application from more than just the top-level
script?

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