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Comment by candiddevmike | Hacker News Reader

I don't know what magic combination it is but I keep hitting something on WSL2 and Windows Terminal that makes my session freeze into a blinking cursor. This results in me having to close the current tab and start a new terminal session completely.

We're still inventing new ways of breaking arguably the most basic user interfaces.

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Probably CTRL-S, which is the software XOFF flow control. If so, CTRL-Q sends XON, which will un-hang the session and resume data flow.

Ah yes, CTRL-Q, the most intuitive keybind for resuming a frozen terminal after pressing CTRL-S, the least likely combination to accidentally be pressed while typing.

It's mnemonic! [S]top and [Q]ontinue :o)

[Q]ontinue was the next best option, c is already taken up to [C]ill the current process obviously.

Reminds me of the game NetHack. How do you consume a potion? Well, you [q]uaff it, of course!

They really should have switched the latter with Verti[k]al Tab.

CTRL-whatever does something funky often enough that I only hit CTRL on purpose.

Stop/Qontinue.

x & 0x1F is what the Ctrl Key used to do, with x being the other keypress. This made the ascii control characters accessible using the Control key (hence the name). So you can access Tab with Ctrl+I, the newline characters with Ctrl+J and Ctrl+M, the backspace with Ctrl+H and also XON and XOFF with Ctrl+Q and Ctrl+S.

They weren’t chosen with mnemonics in mind, because there are 32 of them. You might be interested in the keyboard on the IBM Model 33 teletype (<https://en.wikipedia.org/wiki/File:TTY33ASR.jpg>) which had labels for many (but not all) control characters directly on the keycaps.

That’s fascinating. I’m embarrassed to have been making fun of our elder gods without even realizing it. They really were gods for creating such devices, given the constraints at the time. I doubt I could’ve done much better.

The most interesting part is that we still use the same keybinds by default 60 years later. Defaults matter a great deal, but one does not expect a 60 year example.

Cheers for this. Have a wonderful weekend!

There’s really no need to be embarrassed; we do a really poor job of teaching people these things.

Honestly, it’s basically all path dependence. Features get added all the time, but we just keep layering them on top. A lot of the features that already exist are still useful, so none of them can be removed.

IBM was never the manufacturer of the Model 33. It was designed, made and sold by the Teletype Corporation.

Huh, you’re right. I’ve been misremembering that for years apparently.

This can be disabled.

This has JUST started to happen to me recently a few months ago, when sshing into a server and running screen with an emacs inside.

When I reconnect and restart screen back into emacs, ^S pauses output instead of doing an incremental search.

I have to pop out of screen with the right escape sequence to get to the login shell I ran it in, then go "stty -ixon" to disable XON/XOFF flow control. Or always remember to do that before running "screen -RD".

But I never ASKED for flow control, and it has worked PERFECTLY for decades without ever getting into +ixon mode, until just a few months ago, and now it happens every single time.

Did something change recently, is ubuntu auto-installing earth shattering patches that maliciously change the default tty settings behind my back (because XON/XOFF flow control suddenly became cool again?), or did I take a walk on a foggy night and accidentally slip into an alternate universe where it's always been that way for everyone else, and I'm about to be seized by silent men in white coats and taken asylum which turns out to be a rehab clinic for people who can't read minds?

https://en.wikipedia.org/wiki/All_the_Myriad_Ways

I finally gave up and put an "stty -ixon" in my .bashrc, but I get the ominous feeling that's one of those tempting but dangerous kludges you're not supposed to do -- Isn't there a superstition about never touching your tty in an rc file? Or is that never touching your pp in a login file? -- that can come back and bite you in the ass later when you least expect it.

It seems like this is just the latest in a long series of cascading ass bites.

Terminals in UNIX systems are anything but basic. Windows terminal takes it to the extra level by supporting two OS terminal models.

Terminals in non UNIX, that not pretend to be serial printers, like the Amiga DOS, or plain MS-DOS, those are the basic ones.

Windows might even support 3 if you count cmd and powershell separately :lolsob:

cmd and powershell are shells, not terminals.

The Amiga terminal is simple in some ways, but it supports stuff most Unix terminals, won't, such as the ability to shift the text positioning by individual pixels in both x and y direction, which was of course promptly "abused" to draw bitmap graphics (exceedingly slowly) to the terminal.

MS-DOS had ANSI support with ANSI.SYS [0], that support never got into Windows NT's CMD.COM.

[0]: https://en.wikipedia.org/wiki/ANSI.SYS

Yeah, but that is a device driver, not part of the command.com itself.

You are conflating and confusing several different things, including what operating systems even had a terminal paradigm. Windows NT started out with a "console" paradigm, like OS/2 before it, not a "terminal" one. And command processors like CMD are not what provide the "console" parts of those systems.

I keep doing this in gnome-terminal, and for years I was confused about what was going on, I thought it was a bug, but I found out what it is! It turns out there is a "read-only" mode, with some keyboard shortcut that I was triggering by accident. You just have to right click in the terminal and uncheck "read-only" to get it back.

Dunno how long it's been since you used it, but I believe keybindings for this are disabled by default now and you have to toggle them on in your profile preferences.

control-Q and control-S freeze/unfreeze the output stream (can't remember which is which). May be that?

It doesn't seem to be that, I can't even reliability reproduce it. I originally thought it was something with the right control or right alt, but it's not consistent.

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