Hello,

Steps to reproduce:
- Boot the Debian installer
- At the boot menu, select "Graphical rescue mode"
- follow steps until "Enter rescue mode"
- Select a Debian root device
- Select "Execute a shell in <selected root device>"
- in the shell, execute "dpkg-reconfigure keyboard-configuration"
(any other installed package than keyboard-configuration which has
configuration questions will do too)

Output:
debconf: unable to initialize frontend: Newt
debconf: (Can't locate Debconf/FrontEnd/Newt.pm in @INC...)
debconf: falling to frontend: Noninteractive

Forcing --frontend=dialog or readline does not help.

This seems to be caused by the DEBIAN_FRONTEND=newt environment variable
leaked from the graphical installer. It does not happen in the text
installer nor in tty2/tty3 shells.

Not sure if this bug should be assigned to debian-installer, rescue-mode
or debconf which should ignore DEBIAN_FRONTEND if invalid or superseded
with --frontend. The issue also happens when selecting "Execute a shell"
from the main menu and executing chroot manually, so it is not specific
to rescue-mode.

Hi Pascal,

Pascal Hambourg <pascal@plouf.fr.eu.org> (2022-01-24):

Maybe it would make sense to just unset that variable when entering a
shell in such conditions… but then I don't know anything about that code
path. A quick search suggests start-shell in debian-installer-utils,
which incidently has specific handling based on $DEBIAN_FRONTEND…


Cheers,