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Re: Use of installer's interactive shells on tty1-tty4

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On Mon 14 Sep 2020 at 19:48:37 (+1000), David wrote:
> On Mon, 14 Sep 2020 at 04:05, Felix Miata <mrmazda@earthlink.net> wrote:
> > Richard Owlett composed on 2020-09-13 05:15 (UTC-0500):
> 
> > > Where can I find description of using installer's interactive shells on
> > > tty1-tty4?
> 
> > 1,3,4 are not available shells.
> > IIRC:
> 
> That does not match my recent experience.

Ditto.

> To explore and confirm and maybe learn something from
> smarter people, I report below some actual test results:
> 
> I begin by booting the buster installer on real hardware,
> and it stops at "Debian installer main menu".
> 
> Pressing alt-F2 or alt-F3 produces a prompt
> "Please press Enter to activate this console."
> and pressing Enter starts BusyBox.
> Pressing alt-F4 displays logs.
> Pressing alt-F5 or any higher F-key does nothing.

You can also confirm this by pressing Alt-→ and Alt-← to rotate
through the four VCs.

> Pressing alt-F1 returns to the installer.
> 
> BusyBox 'tty' command confirms /dev/tty2 and /dev/tty3.
> 
> 'echo foo >/dev/tty4' confirms that the log display is
> /dev/tty4 when the string 'foo' appears there.
> 
> I was unable to find any evidence for the use of /dev/tty1,
> apart from pressing alt-F1 working as expected.
> 
> But I was just poking around cluelessly for curiosity, someone
> else might know a way to do that. BusyBox 'ps' appears to not
> provide tty information.
> 
> In BusyBox, 'ls -R' appears unsupported, so I ran:
>   find /proc -type d -exec ls -l '{}' \; 2>/dev/null | grep tty1
> it gave no output.
> 
> I looked at the other active processes using the same methods
> without discovering anything else about /dev/tty1.
> 
> The installer PID was 257.
>   ls -l /proc/257/fd/
> shows
>   2 -> /dev/tty0
> 
> BusyBox 'echo' to /dev/tty0 did not affect the installer screen.
> 
> However, I saw that process '/usr/bin/main-menu' used /dev/pts/0
> and 'echo' to that device did write text into the installer screen.
> 
> At the "Debian installer main menu" I activated the
> "Execute a shell" menu entry. In this shell
> $ tty
> /dev/pts/0
> 
> It appears that /dev/pts/0 performs the role of /dev/tty1.

You found it. That's the shell I said I've never used, available
on VC1 for those unlucky enough to find no means of leaving VC1
(eg Alt/Windows/etc keys not functioning correctly):

> I'm not very knowledgeable about all this tty stuff so I will leave
> it at that.

Same here. An interesting search.

Cheers,
David.

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Thread

Use of installer's interactive shells on tty1-tty4 Richard Owlett <rowlett@cloud85.net> - 2020-09-13 12:20 +0200
  Re: Use of installer's interactive shells on tty1-tty4 Linux-Fan <Ma_Sys.ma@web.de> - 2020-09-13 12:50 +0200
  Re: Use of installer's interactive shells on tty1-tty4 David <bouncingcats@gmail.com> - 2020-09-13 12:50 +0200
    Re: Use of installer's interactive shells on tty1-tty4 Richard Owlett <rowlett@cloud85.net> - 2020-09-13 14:00 +0200
  Re: Use of installer's interactive shells on tty1-tty4 David Wright <deblis@lionunicorn.co.uk> - 2020-09-13 17:40 +0200
  Re: Use of installer's interactive shells on tty1-tty4 Felix Miata <mrmazda@earthlink.net> - 2020-09-13 20:10 +0200
    Re: Use of installer's interactive shells on tty1-tty4 David <bouncingcats@gmail.com> - 2020-09-14 11:50 +0200
      Re: Use of installer's interactive shells on tty1-tty4 David Wright <deblis@lionunicorn.co.uk> - 2020-09-14 16:20 +0200
        Re: Use of installer's interactive shells on tty1-tty4 David <bouncingcats@gmail.com> - 2020-09-14 20:30 +0200
          Re: Use of installer's interactive shells on tty1-tty4 David <bouncingcats@gmail.com> - 2020-09-14 20:50 +0200
            Re: Use of installer's interactive shells on tty1-tty4 David Wright <deblis@lionunicorn.co.uk> - 2020-09-15 18:40 +0200
              Re: Use of installer's interactive shells on tty1-tty4 Felix Miata <mrmazda@earthlink.net> - 2020-09-15 20:50 +0200
                Re: Use of installer's interactive shells on tty1-tty4 David Wright <deblis@lionunicorn.co.uk> - 2020-09-16 04:40 +0200
                Re: Use of installer's interactive shells on tty1-tty4 Felix Miata <mrmazda@earthlink.net> - 2020-09-16 06:10 +0200
      Re: Use of installer's interactive shells on tty1-tty4 Stefan Monnier <monnier@iro.umontreal.ca> - 2020-09-14 19:20 +0200
        Re: Use of ^Hi^Hn^Hs^Ht^Ha^Hl^Hl^He^Hr^H'^Hs interactive shells on  tty1-tty4 Felix Miata <mrmazda@earthlink.net> - 2020-09-14 20:00 +0200

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