On Fri, Mar 8, 2019 at 8:46 PM Chris Murphy <lists@colorremedies.com> wrote:
There's a new feature in Fedora 29, hide the grub menu, that can make
it difficult to troubleshoot system upgrades if you run into a
problem. Here's what you can do to get more information for a one time
boot without obliterating the default behavior you'll maybe want for
future testing:

- enable a one time show boot menu for 60 second
$ sudo grub2-editenv - set menu_show_once=1

- Now do `dnf system-upgrade reboot`

Or you can simply mash F8 on reboot to show the grub menu, right? Seems easier than remembering the grub command.

 

- At the grub menu insert the following boot parameter
systemd.debug-shell=1

That enables early debug shell, soon after systemd is running. The
shell is on tty9, and it gives root access without credentials
required! Super powerful, and super duper security risk. So I advise
adding it only at the grub menu, for one time use.

That's useful. Thanks for a tip.