In this video, I would like to give you
an overview of your different options for troubleshooting
the boot procedure.
So the first thing you need is GRUB.
In case you cannot go to GRUB, there's one option only,
and that is the boot disk.
That's a rescue disk.
Your installation disk, your L10 installation disk
can be used to boot from a separate kernel.
So you can start a different kernel
that runs Linux for you.
Now, if you do get to GRUB, then there is the GRUB prompt.
And all other options are really happening in the GRUB prompt.
The first option that is convenient
allows you to break in right here,
right before you are using systemd.
And that is the option init is slash bin slash bash.
You need this option in case anything is going wrong
that is managed by systemd.
Now, in case you do get to your systemd,
there's another option.
And the other option allows you to break in
before the completion of the early boot.
That will be systemd.unit equals emergency.target.
And the last option that is relevant
is where you can boot your rescue target.
So here again, systemd.unit equals rescue.target.
Now, as you can easily see, the difference
between the rescue target and the emergency target
is that in the rescue target, you did process your early boot.
And the emergency target is bringing you in before that.
Now, as a generic guideline, if you
are troubleshooting a system that doesn't want to boot,
get as much of your system up as possible,
which means that if you identify that your problem is here
in early boot, well, systemd.emergency.target
is going to be the solution.