Re: Setup patch to keep test version if test version installed

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Feb  6 12:25, Achim Gratz wrote:
> Corinna Vinschen writes:
> > On Feb  5 22:57, Achim Gratz wrote:
> >> 
> >> Oh, and while you are so deep in the bowels of setup.exe, would it be
> >> possible to somehow fake a pty to shell scripts and a console to cmd so
> >> that the scripts run by setup.exe produce their output in line-buffered
> >> instead of fully buffered mode?
> >
> > Er... uh... *cough*... PTC?
> 
> I was hoping you had an idea of how to do this.  I'm coming up empty.
> 
> > For Cygwin processes this would require to duplicate lots of the pty
> > code from Cygwin to Setup.  For native commands it might be enough to
> > play with the process creation flags in the call to CreateProcess, but
> > that might lead to a flickering taskbar entry for a hidden console.
> 
> I've tried to look for recipes, but have not found any that look promising.
> 
> http://www.pixelbeat.org/programming/stdio_buffering/
> 
> I notice the lack of both unbuffer and stdbuf in Cygwin packagesâ

Unbuffer should be in the expect package, stdbuf in coreutils.  In both
cases I don't know why they are missing in Cygwin.

Yaakov?  Eric?

> IÂdon't think it's possible to ask another application to flush their
> buffers or is there?

If the application isn't prepared to do that (e.g. via signal), no.

> > The other problem is that the stdio handles are redirected to a file
> > and thus, even if you have a console or pty, the output from the command
> > will use fully buffered mode.
> >
> > The only way around that, afaics, is some sort of global setting (env
> > var?) for the buffering mode which is honored by native processes and
> > which may be read by the Cygwin DLL as well to enforce line buffering.
> > But I'm not aware such a setting exists.
> 
> Doesn't sound appealing.  Maybe we just have to live with it.

Looks like it, sorry.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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