Re: misbehavior in shell window with ksh

[Eli Zaretskii <eliz@gnu.org>]

> From: Stephen Berman <stephen.berman@gmx.net>
> Cc: mkupfer@alum.berkeley.edu,  emacs-devel@gnu.org
> Date: Thu, 04 May 2017 09:54:23 +0200
> 
> > The above is the interesting part: it shows that the "> " string was
> > received from the shell subprocess.  And that rings a bell: we have
> > this window-adjust-process-window-size-function feature, which is new
> > in Emacs 25.  It sends a TIOCSWINSZ or TIOCSSIZE ioctl to the shell's
> > pty; perhaps that causes the shell to respond with PS2?  Can you play
> > with the value of this variable, like set it to a function that
> > returns nil, so that set-process-window-size is not called, and see if
> > that helps to avoid the issue?
> 
> Bingo!  That variable is a user option and when I change its value with
> M-x customize-option to "Do not adjust process window sizes" (i.e. the
> function `ignore') and then execute the recipe, "> " is not inserted.
> When I return to the customization buffer and change the value back to
> the default "Minimum area of any window" (i.e. the function
> `window-adjust-process-window-size-smallest') and then switch back to
> the *shell* buffer, "> " I see that has now been inserted.

Thanks for looking into this.

Can the shell experts among us please tell whether this is an expected
reaction of a shell to window-resizing ioctl?  And why this is only
seen with ksh?  And why in some cases one needs to set EDITOR in the
environment?

IOW, the window-adjust-process-window-size-function is a standard
feature that is turned on by default; if it turns out that it has
annoying unintended consequences in some use cases, we will have to
rethink when we turn it on and off, IMO.