25 Jul
2020
25 Jul
'20
9:09 p.m.
BTW: another old V6 trick is the use file redirection from the different
terminal to unlock a hosed tty. Programming on the console was
fraught with multiple dragons and not recommended. But due to program
crashes that left things in raw mode, I admit that I remember having to
uses the redirection trick a few times to get the console back. As Noel
said, it could get dicey if the console ended up with canonicalization
turned off. V7's ½ cooked (*a.k.a.* CBREAK) was a welcomed edition, but
the fact is V6's try handler was good enough most needs and a lot of used
it pretty successfully for a long time.
Clem
On Sat, Jul 25, 2020 at 12:02 AM John Cowan <cowan(a)ccil.org> wrote:
Ctrl+J actually is the keystroke for U+000D LINE FEED,
so it always works;
old-timers got in the habit of typing ^Jreset^J.
Note that if a program gets stuck in rare mode rather than raw mode, you
can get out of it with ^C (or whatever INTR is set to), a good reason for
using rare mode.
On Fri, Jul 24, 2020 at 10:49 PM Paul Riley <paul(a)rileyriot.com> wrote:
> Yep already fallen into that trap. Glad I'm running on a sim! Yes I'd
> considered writing a small program to reset the STTY settings, and you've
> helped me to understand how I can run it!
>
> In answer to the CR question, is it that in raw mode, the CR does not get
> mapped to LF, and therefore the shell doesn't see the LF character and
> recognize the end of the line? Incidentally, why the ^J before ft? Just to
> clean up the shell input status?
>
> I'll write my own ft, thanks. I'll try raw mode, because I want some
> better line editing capability.
>
> Alternatively if I toy around with /dev/tty does that interfere with the
> operation of the standard console outside of my app?
>
> Paul
>
> *Paul Riley*
>
>
>
>
> On Fri, 24 Jul 2020 at 22:36, Clem Cole <clemc(a)ccc.com> wrote:
>
>>
>>
>> On Thu, Jul 23, 2020 at 10:29 PM Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
>> wrote:
>>
>>> ...
>>> This is not a C issue; it's the Unix I/O system (and specifically,
>>> terminal I/O).
>>
>>
>>> ...
>>
>> One can suppress all this; there's a mode call 'raw'
>>>
>> Just be sure to turn raw mode off so canonization is performed again
>> after your program stops running. Remember this a 'system wide'
>> settings for that try and all programs start to use that setting. So if
>> some reason, your program stops and a new program (like the shell) takes
>> back over input from the try, if you do not have a way to get it back you
>> are screwed.
>>
>> Back in the day, I have a shell script in my path stored in ~/.bin
>> called: ft (fix tty) which called the stty command with the way I
>> wanted the terminal to be set up. Thus is I was running a program
>> that core dumped and left the try in raw mode, if I could find a way to run
>> the ft script (usually by typing ^Jft^J ) life was good again. Paul,
>> as an exercise why would ft<CR> not be good enough? (hint read and
>> study the section 4 man page for stty)
>>
>> FWIW: is how the original UCB ex/vi and Cornell's Fred editors for v6
>> works by the way. I suspect that iyou look at any of the video editors of
>> the day it will show you the details.
>>
>> One of the differences between V7 and earlier UNIX tty handlers was that
>> they tty canonization was split into multiple parts. Also the other hint
>> with Sixthedition's version of raw and cooked modes, you get all or nothing
so
>> you if you turn on raw, your program, will have do things like backspace
>> processing, *etc*..
>>
>>