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Author Topic: REISUB sequence  (Read 323 times)

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Offline arky217

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REISUB sequence
« on: May 02, 2018, 09:50:56 am »
I have a Insignia keyboard and it does not have a SysRq key.
So, to use the REISUB sequence if my computer should lock up,
what key combination would I use when entering the REISUB keys ?

I've read where the Print Screen key might be the same as the SysRq key.
I've also read that it could make a difference in whether or not you used
the left or right Ctrl or Alt keys.
Also, is the REISUB sequence even enabled in Peppermint 8 ?

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Re: REISUB sequence
« Reply #1 on: May 02, 2018, 10:01:59 am »
On MOST (but not all) non-laptop keyboards, SysRq is the same as the PrtSc (print screen) key.

AFAIK REISUB is enabled in ALL Linux distros, because it's built into the kernel.
(but that's not the same as saying it'll work on all keyboards .. some use non-standard keycodes, or it may not work if you need to use Fn to access SysRq, as on my Dell)
« Last Edit: May 02, 2018, 10:07:10 am by PCNetSpec »
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Offline spence

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Re: REISUB sequence
« Reply #2 on: May 15, 2018, 09:28:13 pm »
This gave me an idea... as REISUB had never worked for me on this slow and kludgey Win10 laptop... but i hadn't been using the alt key that is closest to the FN key... makes for weird finger manouvers, but it worked this time around...
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Offline zebedeeboss

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Re: REISUB sequence
« Reply #3 on: May 16, 2018, 01:32:17 am »
OK really noob question - as it is never stated clearly anywhere I have read.

do you keep alt+PrtSc held down whilst then typing REISUB and is it capital letters or will reisub suffice?

Regards Zeb...

ps NO, I have never tried any such key combinations to test it
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Re: REISUB sequence
« Reply #4 on: May 16, 2018, 07:59:09 am »
Yes you need to hold Alt+Sysrq (some keyboards need it to be AltGr+SysRq instead) whilst typing the others .. and lower case will do, people only capitalise it to show its not a word.

REISUB (where it works at all) should safely reboot the system in ALL cases except a kernel panic .. but remember it won't work on all systems simply because of the way keyboards work .. my Dell for example requires I hold Fn to access SysRq, so it doesn't work.

In case you're interested, here's what the keystrokes are telling the kernel to do...

R = Take control of the keyboard.
E = Tell all running programs/processes (except those from the master control system) to TERMINATE.
I = KILL (with prejudice) any programs/processes which didn't shut down from the previous terminate signal.
S = Force any cached data to be written to the hard-drives.
U = Remount the drives read-only, so nothing else can be written to them.
B = Reboot.

Easy way to remember REISUB=Restart Even If Sytem Utterly Broken
« Last Edit: May 16, 2018, 08:24:03 am by PCNetSpec »
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Offline zebedeeboss

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Re: REISUB sequence
« Reply #5 on: May 16, 2018, 08:07:27 am »
Thank You  :)
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Re: REISUB sequence
« Reply #6 on: May 16, 2018, 08:22:26 am »
Another option is REISO which will power Off the system instead of rebooting it.
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