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I've given it a lot of thought, and below is my one "reformist" idea to significantly improve things without breaking back compat so bad

Invert the shell and terminal: every shell command (with unredirected streams) gets it's own pty.

- Like the those repl "notebooks" you can scroll each output separately, without hacks.

- Backgrounded processes won't spew garbage when you are trying to type. They just continue running in their terminal. You can even background something like vim or a game that takes the whole terminal, and it's just fine!

- Rather than hacking scroll back onto processes that might use tty stuff in expected ways, just straight-jacket them by giving them plain pipes instead! The OP exploits are then opt-in impossible.

- Having powershell-esque "post-text" commands that dispense with the bullshit are far easier to manage: also give them regular file descriptors and negotiate protocol or whatever, just like the above, rather than a pty.

- stdin can be a nice form with submit button rather than fixed (usually line) buffering policy.

- shell might even be simpler as there is less careful juggling of shared resources except where the programmer asks for it.

I also use ssh multiplexing instead of tmux for extra shells. When I do need to use tmux, I hate that read only mode prevents scrollback. The above builds nicely upon this:

- The persistent remote shell has as many ptys as needed before for chained commands which might still be running, or separate "sessions"

- The local client can use native UI elements for everything, no TUI jank.

- Scrolling over many (live or saved) terminals, the normal scrollback case, is possible and very side-effect free.

Anyone see any issues? I don't for anything I do daily (git, coretuils, etc.)! I don't think I have time to make this, so please someone else do.

> You can even background something like vim or a game that takes the whole terminal, and it's just fine!

Focusing on this point, you can background vim just fine right now - I have tons of vim processes backgrounded all the time.

You can suspend vim. If you try to run it in the background (e.g. with the bg command) then it just suspends itself again. To actually run it in the background on a shared terminal you need something like screen or tmux… which assigns the process its own pty.

Perhaps for most use cases involving vim it doesn't make that much difference—what would it be doing in the background anyway?—but there are other TUI programs that could be doing useful processing in the background if they didn't need to share the pty with other processes.

I’ve given this a lot of thought over the years and the biggest conclusion I have is that there’s no real “killer feature” in any of this that makes it spectacular, and maintaining backwards compatibility would be critical to let anybody use it. Still, I like the idea of splitting each command into a separate PTY, I wonder how good a TUI replacement for tmux built around this could be (yes, gotta start with the TUI before you think about a completely new GUI, again for the interop).

It's not a direct match, but I think you'd be fascinated by aspects of Plan9's model. It certainly comes closer to what you've described than Unix does. Depending on exactly what you mean or you're envisioning, it might be really close.

The problem, of course, is this either breaks existing software or requires new software to be written from scratch to utilize the new frameworks. This was (one of) the reasons plan9 never gained much traction, and the big hurdle for any contender to the TTY/shell throne.

(It's also worth pointing out microsoft themselves reworked their terminal interfaces to be more unix-like for this very reason -- software compatibility)

Yes please. I've often thought the same.

Mentioned this comment here: https://blog.williammanley.net/2021/03/31/seen-on-hn-invert-...

You’d need to implement a new protocol between terminal and shell. Maybe the shell would be in charge - allocating PTYs and multiplexing the output back to the terminal. Or maybe the terminal would be in charge where it would allocate PTYs for children and send them to the shell using FD passing. There are advantages both ways.

Integral to its success though would be getting the support for this new protocol upstream in bash. Bash is the most widely deployed shell and the only way to get to the point where you can log in to a new machine (or over SSH) and expect this to “just work”. Without that it would remain a niche and could join the graveyard of other improved shells/terminals that approximately no-one uses.

As such the protocol would have to be minimal and easily implementable in C. Systemd’s protocols could be an inspiration. I’ve implemented both sides of sd_notify and LISTEN_FDS before, in more than one programming language and it was very straightforward.

I’m working on exactly this right now. I’d love to chat and show you what I’m up to; if you’re interested, email me at noah@coterm.dev

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