[SOLVED] How do you reboot a server when Systemd is unavailable?

shanebagel · 06-15-2022, 07:11 PM

I'm in minimal mode trying to reset the root users password.
"System has not been booted with systemd as init system (PID 1). Can't operate"

I can't run any systemctl commands as the systemd daemon is unavailable. If you didn't have direct console access to this server - how would you reboot it? Other than just pulling the plug physically, and booting it back online?

evo2 · 06-15-2022, 08:54 PM

What init system is it using?

Anyway, regardless of the init system in use, most will have a halt and/or reboot command.

Evo2.

michaelk · 06-15-2022, 09:08 PM

Not necessarily, if the OP used init=/bin/bash then as a shell process there isn't any basic power management commands available.
In my ignorance I just stopped the process via the exit command and virtually pulled the plug (I was playing with a VM). Here is one way...

Quote:

echo 1 > /proc/sys/kernel/sysrq
echo b > /proc/sysrq-trigger

https://www.linuxjournal.com/content...ting-magic-way

You should unmount any filesystem that you manually mounted as well as remount /(root) as read only.

evo2 · 06-15-2022, 09:15 PM

Quote:

Originally Posted by michaelk

Not necessarily, if the OP used init=/bin/bash then as a shell process there isn't any basic power management commands available.

Good catch. I missed the first line in OPs post :

Quote:

Originally Posted by shanebagel

I'm in minimal mode trying to reset the root users password.

Cheers,

Evo2.

shanebagel · 06-16-2022, 11:46 AM

I didn't realize you can just exit the shell lol.
Thanks all!

boughtonp · 06-16-2022, 11:53 AM

See https://www.kernel.org/doc/html/latest/admin-guide/sysrq.html and https://en.wikipedia.org/wiki/Magic_SysRq_key

Quote:

Originally Posted by https://en.wikipedia.org/wiki/Magic_SysRq_key

A common use of the magic SysRq key is to perform a safe reboot of a Linux computer which has otherwise locked up (abbr. REISUB). This can prevent a fsck being required on reboot and gives some programs a chance to save emergency backups of unsaved work. The QWERTY (or AZERTY) mnemonics: "Raising Elephants Is So Utterly Boring", "Reboot Even If System Utterly Broken" or simply the word "BUSIER" read backwards, are often used to remember the following SysRq-keys sequence:

unRaw (take control of keyboard back from X),
tErminate (send SIGTERM to all processes, allowing them to terminate gracefully),
kIll (send SIGKILL to all processes except init, forcing them to terminate immediately),
Sync (flush data to disk),
Unmount (remount all filesystems read-only),
reBoot.