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From: John Cowan <>
To: Will Senn <>
Cc: TUHS main list <>,
	Noel Chiappa <>
Subject: Re: [TUHS] svr2 delete behavior
Date: Mon, 27 Dec 2021 18:52:17 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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On Mon, Dec 27, 2021 at 9:56 AM Will Senn <> wrote:

> I hadn't tried it in v6 in a while. I'd pretty much resigned myself to #
> and @. But I see the effect in v6, even without changing stty and it
> 'works', but in svr2, if I type lsa and then hit ^H it backs up a place,
> but then when I press enter the shell says something along the lines of -
> lsa^H: not found.

That's exactly what you expect when ^H is not magic: it is echoed back to
/dev/tty like any other normal character, and your emulator does what ^H
means per X3.4: it backs up the cursor by 1 column.

But by adding stty erase ^H, it then 'works' the same as in v6. Seth's
> steer regarding setting erase and echoe 'fixed' things, once I figured out
> that having DEL doubling as intr wasn't ideal.

A nice hack in stty (though I am not sure how far back it goes): you can
enter ^H either with an actual backspace character or with the
two-character sequence ^ followed by h or H.  The second form has the
advantage that it can be typed correctly no matter how badly you have
screwed up your control characters.

Oh, the mysteries of terminal interaction.

Not _that_ mysterious.  Grab ECMA standard 48 (technically equivalent
to ANSI X3.64) at <>
you'll know all about how terminal emulators behave.  It isn't hard to
read, once you have learned to read "00/13" as hex 0D, which everyone knows
right off is CR.  (If not, <> is your friend.)  The reason
for this bizarre row/column notation is so that escape sequences are always
binary no matter the encoding: the sequence that introduces multi-character
control sequences is usually spoken of as "ESC [", but technically it has
to be sent to a conforming terminal as "\x1B\x45" even if the encoding is
EBCDIC, where "ESC [" would be "\x27\xBA" (at least in the US/Canada flavor

Bugs are another matter, of course.


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  reply	other threads:[~2021-12-27 23:53 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-27 14:37 Noel Chiappa
2021-12-27 14:56 ` Will Senn
2021-12-27 23:52   ` John Cowan [this message]
  -- strict thread matches above, loose matches on Subject: below --
2021-12-27  0:31 Will Senn
2021-12-27  1:24 ` Seth Morabito
2021-12-27 14:39   ` Will Senn

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