[PATCH] Cygwin: pty: Disable clear screen for ssh sessions with -t option.

[Takashi Yano]

Hi Corinna,

On Fri, 18 Oct 2019 16:33:06 +0200
Corinna Vinschen wrote:
> Sorry, but this doesn't look feasible.
> 
> You can't base the behaviour on the name of an application.  What about
> other applications like telnetd, rshd, just to name the first ones
> coming to mind?  What about a renamed sshd, or sshd installed into
> another directory, or just an sshd in the build dir during testing?
> 
> Is this workaround really necessary at all?  Even basing this on the
> terminal name looks pretty fragile.

I agree with you. However, I couldn't come up with better method.
Now I have come up with another implementation. Could you please
have a look at v2 patch?

As a caution, this patch is for:
https://www.cygwin.com/ml/cygwin/2019-10/msg00074.html
therefore, telnetd or rshd is not targeted.

> Why exactly is the clear screen necessary?  You wrote something about
> synchronizing the pseudo console and the pseudo tty content, IIRC, but
> it still seems artificial to enforce a clear screen.  Is there no
> other way to make the pseudo console happy?

Using cygwin 3.1.0-0.7 (TEST), by the following steps, you can see
what happens if clear screen is not done.

1) Execute ls or ps to draw something to screen.
2) env TERM=dumb script
3) Execute cmd.exe.

If we can accept this behaviour, clear screen is not necessary.

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>