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Message-ID: <ffa582e2-601f-44b4-86c8-3bfb5d562a9c@acm.org>
Date: Sat, 5 Jul 2025 09:17:34 -0700
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Subject: Re: mintty-bash-ssh weirdness after remote disconnect during vi
 session
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To: cygwin AT cygwin DOT com
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From: Jim Garrison via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Jim Garrison <jhg AT acm DOT org>
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On 7/4/2025 18:49, Thomas Wolff via Cygwin wrote:
> 
> Am 05.07.2025 um 03:04 schrieb Jim Garrison via Cygwin:
>> I've recently started seeing weirdness in mintty/bash after a 
>> connection to a remote system is terminated by the remote.  So far 
>> this seems to happen only if the remote session was interrupted while 
>> vi was running.
>>
>> After the session is interrupted, here's what happens on the local 
>> (Windows/cygwin) mintty window:
>>
>> * Ctrl-D just rings the tty "bell"
>>
>> * Any change of window focus, in Windows, for the mintty window itself,
>>   causes the tty bell to ring
>>
>> I researched this by opening a second terminal session and using that 
>> to kill various processes in the remote tree: ssh-bash-vi and found 
>> that just killing the vi process causes the issue.  On the remote 
>> system, Ctrl-D produces the string "0;5u".  Exiting the remote session 
>> (via 'exit') then leaves the local mintty in the same state.
>>
>> I guess it's because vi remaps keystrokes and they didn't get reset 
>> when vi died, but my usual goto 'stty sane' does not fix the problem, 
>> neither on the remote nor local systems.
> Certainly a good guess. You can check your state with `stty -a`, for 
> example about ^D behaviour.
> 
>> Is there a way to reset mintty other than closing and reopening it?
> Try the `reset` command. Or the `Reset` function from the context menu, 
> also via Alt+F8.

`reset` does the trick.  However my curiosity is piqued since it appears 
the remote vi somehow remapped a lot of keystrokes in the local mintty. 
In fact, it seems to have mapped ALL the uppercase letters to escape 
sequences... but left all the lowercase letters, numbers and puctuation 
alone.

Interesting, but probably not worth spending any time on. It's just part 
of the "undefined but not really unexpected" behavior when you pull the 
rug out from under a program that remaps terminal keystrokes for its own 
use :-)

-- 
Jim Garrison
jhg AT acm DOT org

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