On Mon 08 Feb 2021 at 13:02:21 (-0800), David Christensen wrote: > On 2021-02-08 00:40, Marco Möller wrote: > > > You could bypass any password request during boot to the console > > and then fix it by setting the desired password newly. The boot > > parameter for bypassing all password request an right away > > becoming logged in as user root is: > > init=/sbin/sulogin --force > > That is interesting. But, how does the reader *use* that information. > STFW 'site:debian.org boot parameters buster', I see: > > https://www.debian.org/releases/buster/arm64/ch05s03.en.html > > Skimming the page, I do not see any instructions for entering boot > parameters...
Perhaps it's not made obvious enough there. The page starts with "Boot parameters are Linux kernel parameters", and the footnote (labelled ²) hints that they're given on the kernel command line, ie the line starting with "linux" in grub.cfg. > Following the link 'Linux BootPrompt HOWTO': > > https://tldp.org/HOWTO/BootPrompt-HOWTO.html > > SSL problems. Try another site: > > http://linuxdocs.org/HOWTOs/BootPrompt-HOWTO.html > > I see LILO. Wow. Remember LILO and the 90's? Some of these HOWTOs are interesting reminders of how we used to configure things. Keeping such internal references up to date is a tough task. Perhaps googling is more productive. > STFW 'linux boot prompt', I see: > > https://www.linuxquestions.org/questions/linux-newbie-8/linux-boot-prompt-4175659396/ > > The answer by djk44883 provides a link to the GRUB manual: > > https://www.gnu.org/software/grub/manual/grub/grub.html Yes, that the place I look these things up. > '5.3.2 GNU/Linux' looks relevant: > > https://www.gnu.org/software/grub/manual/grub/grub.html#GNU_002fLinux > > But nothing tells me how to get to the 'grub>' prompt... I think that section is for people building a grub.cfg from scratch. You want §14.2, which describes the menu interface that we're all familiar with. > Booting a Stretch system, I see a menu: > > GNU GRUB version 2.02~beta3-5+deb9u2 > > *Debian GNU/Linux > Advanced options for Debian GNU/Linux > > Use the ? and ? keys to select which entry is highlighted. > Press enter to boot the selected OS, 'e' to edit the commands before > booting, or 'c' for a command line Yes, that summarises §14.2 … > If I press 'e', it (GRUB?) appears to bring up an editor window that > contains a bunch of content that looks relevant. The last few lines > are: > > .... > echo 'Loading Linux 4.9.0-9-amd64 ...' > linux /vmlinuz-4.9.0-9-amd64 root=UUID=... ro noresume > echo 'Loading initial ramdisk ...' > initrd /initrd.img-4.9.0-9-amd64 … and that's the menu version of the commands outlined in 5.3.2. > If I press 'c', I obtain a prompt: > > grub> You don't want that, which is what you get when Grub gets lost. > Do I add 'init=/sbin/sulogin --force' in the editor? Yes, to the linux line: it's a kernel parameter. Why no 'set'? Because "init" is not a Grub variable. > Where is this documented? I always go to https://www.kernel.org/doc/html/v4.15/admin-guide/kernel-parameters.html (where v4.15 could be different). init= [KNL] Format: <full_path> Run specified binary instead of /sbin/init as init process. where KNL confirms it's a Kernel parameter. The introduction shows: BUGS= Relates to possible processor bugs on the said processor. KNL Is a kernel start-up parameter. BOOT Is a boot loader parameter. Cheers, David.