"tmux open terminal failed: not a terminal" in terminal emulators other than mintty

"tmux open terminal failed: not a terminal" in terminal emulators other than mintty

[Kacper Michajlow]

Hi,

I'm not exactly sure who to blame for this issue, but I figured I will ask
you guys. Tmux fails to open in anything else than mintty it seems like. It
works from ssh session, probably because pseudo-tty is allocated, but
except that tmux will fail.

There are multiple reports about that, without solutions:
https://github.com/cmderdev/cmder/issues/453
https://github.com/alacritty/alacritty/issues/1687
https://github.com/zeit/hyper/issues/3608
https://github.com/microsoft/terminal/issues/5132

Do you think we could make it work without using mintty?
If yes, should the changes be made in the Cygwin, tmux or terminal emulator
code?
Any pointer would be good so I can poke others :)

Thanks,
Kacper

Re: "tmux open terminal failed: not a terminal" in terminal emulators other than mintty

[Andrey Repin]

Greetings, Kacper Michajlow!

> I'm not exactly sure who to blame for this issue, but I figured I will ask
> you guys. Tmux fails to open in anything else than mintty it seems like. It
> works from ssh session, probably because pseudo-tty is allocated, but except
> that tmux will fail.

> There are multiple reports about that, without solutions:
> https://github.com/cmderdev/cmder/issues/453
> https://github.com/alacritty/alacritty/issues/1687
> https://github.com/zeit/hyper/issues/3608
> https://github.com/microsoft/terminal/issues/5132

> Do you think we could make it work without using mintty?

You can try another pty emulator. F.e. wintty.

> If yes, should the changes be made in the Cygwin, tmux or terminal emulator
> code?
> Any pointer would be good so I can poke others :)


-- 
With best regards,
Andrey Repin
Thursday, March 26, 2020 22:02:58

Sorry for my terrible english...

Re: "tmux open terminal failed: not a terminal" in terminal emulators other than mintty

[Kacper Michajlow]

> You can try another pty emulator. F.e. wintty.

Not really interested in some dead projects ;p

Let me rephrase the question, because I misspoke.

Currently Cygwin works acceptably only under Mintty as far as I can see.
Running it from cmd or any of terminal emulators listed before result in
sub-par performance. Even things like Home button to move cursor doesn't
work, as originally stated tmux doesn't work and so on.

Now that Windows is making improvements to their console
https://devblogs.microsoft.com/commandline/windows-command-line-introducing-the-windows-pseudo-console-conpty/
it may be good time to improve Cygwin's compatibility.

Since my first mail I looked at git log and seen pty related changes,
compiled latest Cygwin, but it doesn't work better and even worse, because
mouse stopped working over ssh in tmux.

That said, I guess my really questions are:
1. Is the goal to improve Windows console compatibility?
2. If yes, what is the current status and challenges?
3. And my original question will the tmux work? :)

Projects like Windows Terminal are convenient way to have PS, CMD, Cygwin
and its child MSYS in one window hence I am wondering if it will be
possible without drawbacks.

Re: "tmux open terminal failed: not a terminal" in terminal emulators other than mintty

[Michael Wild]

On Fri, 27 Mar 2020, 14:29 Kacper Michajlow wrote:

> > You can try another pty emulator. F.e. wintty.
>
> Not really interested in some dead projects ;p
>
> Let me rephrase the question, because I misspoke.
>
> Currently Cygwin works acceptably only under Mintty as far as I can see.
> Running it from cmd or any of terminal emulators listed before result in
> sub-par performance. Even things like Home button to move cursor doesn't
> work, as originally stated tmux doesn't work and so on.
>
> Now that Windows is making improvements to their console
>
> https://devblogs.microsoft.com/commandline/windows-command-line-introducing-the-windows-pseudo-console-conpty/
> it may be good time to improve Cygwin's compatibility.
>
> Since my first mail I looked at git log and seen pty related changes,
> compiled latest Cygwin, but it doesn't work better and even worse, because
> mouse stopped working over ssh in tmux.
>
> That said, I guess my really questions are:
> 1. Is the goal to improve Windows console compatibility?
> 2. If yes, what is the current status and challenges?
> 3. And my original question will the tmux work? :)
>
> Projects like Windows Terminal are convenient way to have PS, CMD, Cygwin
> and its child MSYS in one window hence I am wondering if it will be
> possible without drawbacks.
>

Hi

As the maintainer of the tmux Cygwin package I have to admit that I have no
idea how to fix this. Sorry.

Kind regards

Michael

Re: "tmux open terminal failed: not a terminal" in terminal emulators other than mintty

[Kacper Michajlow]

On Fri, 27 Mar 2020 at 21:15, Michael Wild via Cygwin <cygwin@cygwin.com>
wrote:

> Hi
>
> As the maintainer of the tmux Cygwin package I have to admit that I have no
> idea how to fix this. Sorry.
>

Hi,

I did take a look how tmux works and what is going on in Cygwin. Here is
short summary of my findings.

* Tmux sends each client stdio fd to the server through socket. Cygwin does
not support passing file descriptors over to other processes so this fails.
* Tmux has a hack for Cygwin where it opens tty by name provided by
client...

And now there are two cases:

1. When there is no pseudo terminal. cmd.exe, (WT and most other terminal
emulators out there)
* Tmux server will try to open /dev/cons<N> by name provided by client, but
this fails with ENOENT, because server process doesn't see this device.

2. When there is allocated pseudo terminal
* Tmux server will try to open /dev/pty<N> by name provided by client and
actually work.

Is there a way to make tmux work with /dev/cons<N>? I have seen in docs

/dev/cons1	Console device names are pseudo device names, only accessible
...		from processes within this very console session.  This is due
		to a restriction in Windows.

So it likely means that whatever we do it will not be accessible from
another process.

Is this docs still holds true in latest Windows? I have seen a path to
always allocate pty for native applications, maybe this would actually
resolve this problem too.

Best Regards,
Kacper