REISUB - the gentle Linux restart/shutdown

Nili · 2016-11-20 16:15:34

According to Lifehacker a frozen Linux system that's not responding to the Ctrl-Alt-Delete three-finger-salute can be restarted more safely than by pushing the power button (read more)

So, concretely...
Holding down Alt and SysRq (which is the Print Screen key) while slowly typing R E I S U B will get you safely restarted. R E I S U O will do a shutdown rather than a restart.

I have not tested yet myself, I am not caught in a situation where I have to use these. I'll try later once i finish some running jobs...

Did you know about these solution instead Turning OFF the system with power button? According to the comments inside the site appears mostly works.
...has worked anything for you?

Regards,
Nili

Head_on_a_Stick · 2016-11-20 17:00:34

Thanks for the tip Nili but SysRq is disabled by default in BunsenLabs.

Details here:

https://www.debian.org/doc/manuals/debi … _sysrq_key

Nili · 2016-11-20 18:22:25

Hm, didn't know about the security risk. Thanks for let me/us known HoaS.

Apparently It is not recommended by Debian the usage of these shortcuts. So this thread take another direction in security prism of using "Alt and SysRq"

Debian provide a Tip:
From SSH terminal etc., you can use the Alt-SysRq feature by writing to the "/proc/sysrq-trigger". For example, "echo s > /proc/sysrq-trigger; echo u > /proc/sysrq-trigger" from the root shell prompt syncs and umounts all mounted filesystems.

So, We can use other alternate command to save ourself from a potential trouble.
Thanks for the chap9 link HoaS.

Horizon_Brave · 2016-11-20 20:54:14

Jeez, need some finger dexterity for this lol. Pity that it's been deprecated...Damnit, thanks to hackers it's been disabled,... This is why we can't have nice things!

This is pretty cool to know though,:

Magic SysRq Keys

R: Switch the keyboard from raw mode to XLATE mode
E: Send the SIGTERM signal to all processes except init
I: Send the SIGKILL signal to all processes except init
S: Sync all mounted filesystems
U: Remount all mounted filesystems in read-only mode
B: Immediately reboot the system, without unmounting partitions or syncing

Last edited by Horizon_Brave (2016-11-20 20:55:13)

Head_on_a_Stick · 2016-11-20 21:43:21

Horizon_Brave wrote:

thanks to hackers it's been disabled

The correct term is cracker

ohnonot · 2016-11-20 22:12:37

Nili wrote:

Holding down Alt and SysRq (which is the Print Screen key) while slowly typing R E I S U B

how'm a gonna do this with 2 hands?
reminds me of mozart...

Horizon_Brave · 2016-11-21 00:14:25

Head_on_a_Stick wrote:

Horizon_Brave wrote:
thanks to hackers it's been disabled
The correct term is cracker

lol, I"m sorry, I just can't take the term 'cracker' seriously. I know it's far more accurate, and provides a delination between something that's harmless and for fun and knowledge...and something nefarious... but I just can't get this out of my head:

nore · 2016-11-21 04:27:19

ohnonot wrote:

Nili wrote:
Holding down Alt and SysRq (which is the Print Screen key) while slowly typing R E I S U B
how'm a gonna do this with 2 hands?

Back in the days (early 00's) when i had to manage servers, I had to do it a couple of times. I put my little fingers on Alt and SysRq and stretched other fingers for BUSIER. Surely can't do that in accident. Good to know it's not there anymore.

I don't even see SysRq labeled in these modern keyboards.

porkpiehat · 2016-11-21 15:14:32

On my CRUX system (where sysrq is enabled) and Arch system (if I enable sysrq with sysctl) I can hold down the alt key with one hand and type "sysrq-r-e-i-s-u-b" with the other (the sysrq key only needs to be typed once) -- I have used this a few times on both systems.

My keyboard has a labeled sysrq key; I guess it's not modern. But then my machines are all old too.

(edit) I just checked and this also works on my Debian Jessie and sid netinstalls.

Last edited by porkpiehat (2016-11-21 15:20:59)

pvsage · 2016-11-21 17:57:25

I've heard of this. "Raising Equines Is So Utterly Boring." (Yeah, I know it's "Elephants", but you know me, always looking for the ungulate angle. ) Tried it a couple years ago; seems it's been disabled in Debian for quite some time.

Head_on_a_Stick · 2016-11-21 20:36:28

I will have to apologise to everybody for offering misinformation, it seems that my jessie system has '438' set in kernel.sysrq and thus REISUB is possible.

Really sorry about that folks, my only defence is that my jessie laptop doesn't have a SysRq key so I couldn't check for sure...

:8

nore · 2016-11-22 04:23:20

Head_on_a_Stick wrote:

laptop doesn't have a SysRq key

In some models it is Fn+PrtScr, even if it is not labeled.

martix · 2018-03-27 18:58:39

Head_on_a_Stick wrote:

...thus REISUB is possible.

Yep, I can confirm. Just had a freeze the other day and remembered REISUB - it did work.

Edit: As it says in the OP: Alt and SysRq (which is the Print Screen key) while slowly typing R E I S U B.

Last edited by martix (2018-03-27 18:59:29)

Martin · 2018-03-28 05:58:43

martix wrote:

Head_on_a_Stick wrote:
...thus REISUB is possible.
Yep, I can confirm. Just had a freeze the other day and remembered REISUB - it did work.
Edit: As it says in the OP: Alt and SysRq (which is the Print Screen key) while slowly typing R E I S U B.

How do you do that? I have two hands, not three. I can do it with two hands but what about people with smaller hands?
/Martin

Head_on_a_Stick · 2018-03-28 06:52:07

^ I've got to reach for <Fn>+<PrtSc>+<Alt>+{REISUB} :cry:

Donald Trump always has to do hard resets, apparently.

martix · 2018-03-28 08:52:47

^Maybe not, if Stormy gives him a hand.

#1 2016-11-20 16:15:34

REISUB - the gentle Linux restart/shutdown

#2 2016-11-20 17:00:34

Re: REISUB - the gentle Linux restart/shutdown

#3 2016-11-20 18:22:25

Re: REISUB - the gentle Linux restart/shutdown

#4 2016-11-20 20:54:14

Re: REISUB - the gentle Linux restart/shutdown

#5 2016-11-20 21:43:21

Re: REISUB - the gentle Linux restart/shutdown

#6 2016-11-20 22:12:37

Re: REISUB - the gentle Linux restart/shutdown

#7 2016-11-21 00:14:25

Re: REISUB - the gentle Linux restart/shutdown

#8 2016-11-21 04:27:19

Re: REISUB - the gentle Linux restart/shutdown

#9 2016-11-21 15:14:32

Re: REISUB - the gentle Linux restart/shutdown

#10 2016-11-21 17:57:25

Re: REISUB - the gentle Linux restart/shutdown

#11 2016-11-21 20:36:28

Re: REISUB - the gentle Linux restart/shutdown

#12 2016-11-22 04:23:20

Re: REISUB - the gentle Linux restart/shutdown

#13 2018-03-27 18:58:39

Re: REISUB - the gentle Linux restart/shutdown

#14 2018-03-28 05:58:43

Re: REISUB - the gentle Linux restart/shutdown

#15 2018-03-28 06:52:07

Re: REISUB - the gentle Linux restart/shutdown

#16 2018-03-28 08:52:47

Re: REISUB - the gentle Linux restart/shutdown

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