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hpr4137 :: I used reisub key sequence to reboot my frozen Linux computer

A frozen Linux computer can safely be rebooted with the reisub key sequence.

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Hosted by Henrik Hemrin on 2024-06-11 is flagged as Clean and is released under a CC-BY-SA license.
Linux, reisub, SysRq, System Request. 1.
The show is available on the Internet Archive at: https://archive.org/details/hpr4137

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Duration: 00:03:24

general.

In two earlier episodes I have been talking about digiKam photo management software. I hope to come back to that topic in another episode in the future. But not today.

Today I will talk about what happened to me about two weeks ago. Maybe it was because I had used the hibernate state, which I rarely use, that caused my laptop to behave somewhat strange. So I decided to turn it off. It was my Lenovo Thinkpad T460p laptop, running Linux Mint Debian Edition.

So I turned it off the normal way with the soft button inside the operating system. But instead of power off I was shown a full terminal screen with a lot of text what it was doing. But it never came to the conclusion to turn off.

I have learned that in those situations, although tempting, that on Linux I should not force turn off with the physical mechanical power button. I have tried that before on another Linux laptop, and it was not a success, rather the opposite.

What I should do with Linux is to talk with electrodes directly to the central brain, or in other words, call the Linux kernel with help of a system request and by that sidestep the operating system.

A System Request is done with the SysRq key on the keyboard. In this situation I did the reisub key sequence with a system request:

If I hold the System Request key together with the Alternate Alt key, and when still holding them down, I type the letters r, e, i, s, u and b, one by one in a very slow pace, I take seconds between them. Then I release all keys and the machine reboots.

This was very successful for me and the laptop has since then worked as normal.

I use an external full size keyboard that has a System Request key.

But not all laptops has such a key any more. System Request can be reached also on all or most of those laptops with some key combination. But that key combination varies between manufacturers and models.

In the show notes I add a link to a How to geek article about reisub as well as to Wikipedia about System Request:


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Comment #1 posted on 2024-06-14 11:39:30 by Henrik Hemrin

What is actually u in reisub doing in more detail? Is it needed?

I got a question on Mastodon about the need of u action in reisub: if it is really needed and if so why in more detail? I cannot answer. Maybe you can explain?

For reference, see the question and following thread in this Mastodon-link: https://infosec.exchange/@ksaj/112599224158640463

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