Systemd: how to get into rescue mode

[Little Girl]

Hey there,

Volker Wysk wrote:

>Thank you for your answer, but I think you've missed the point. I
>can't type any command after doing "systemctl isolate
>rescue.target". What I type isn't displayed. Nothing at all happens.
>It doesn't look like a rescue shell is running.

This page is for a different operating system, but the symptoms
they're experiencing when going into single-user mode (which is what
the rescue.target is) are just like yours:

https://bbs.archlinux.org/viewtopic.php?id=226555

Sadly, the final post in that thread suggests that the keyboard
simply isn't available in that mode. I'm kind of boggled as to how
they expect you to interact with it without a keyboard, but perhaps
that's an actual oversight on the part of the devs.

>I've got the "systemctl isolate rescue.target" command from that
>article in the LinxUser magazine. They advise to do it when making a
>backup, so there are no more files which are being used by running
>services.

This video claims that the isolate command is only allowed on units
where AllowIsolate is enabled:

https://www.youtube.com/watch?v=7P7ROr1-yjA

The systemd.unit(5) man page says that AllowIsolate defaults to
false, which could explain the behavior you're seeing, but probably
not. It looks like you found the /lib/systemd/system directory. Is
AllowIsolate enabled in your rescue.target file? It is on my system,
but I'm using an older Ubuntu MATE release, so yours may differ.

This video gives a good run-down of the basics of systemctl:

https://www.youtube.com/watch?v=AtEqbYTLHfs

The systemd.special(7) and systemd.target(5) and systemd.unit(5) man
pages may be useful. They go into detail on what the different units
and targets are and how to use systemd in general.

Last, but not least, this situation reminds me of our way of using
non-graphical TTYs. We've never been able to interact with those TTYs
without first using the cd command (cd plus the Enter key).

We don't know why we have that issue on two different machines when
the rest of the world just switches to a TTY and immediately types
commands that work. We haven't seen this mentioned anywhere, but the
cd command works for us every time and we'd be completely stuck and
unable to interact with the TTY without it. We just happened to try
it one day and it worked, so we remembered it. I have to wonder if
your solution will be something you just happen to stumble into quite
by accident as well.

-- 
Little Girl

There is no spoon.