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Reboot machine when everything is hanging

Terminal - Reboot machine when everything is hanging
<alt> + <print screen/sys rq> + <R> - <S> - <E> - <I> - <U> - <B>
2009-02-20 07:28:56
User: dizzgo
Reboot machine when everything is hanging

If the machine is hanging and the only help would be the power button, this key-combination will help to reboot your machine (more or less) gracefully.

R - gives back control of the keyboard

S - issues a sync

E - sends all processes but init the term singal

I - sends all processes but init the kill signal

U - mounts all filesystem ro to prevent a fsck at reboot

B - reboots the system

Save your file before trying this out, this will reboot your machine without warning!


Know a better way?

If you can do better, submit your command here.

What others think

doesn't work on fedora ;=s

Comment by renich 373 weeks and 6 days ago

This works! (but here's hoping you don't have to use it. :-)

Comment by mpb 373 weeks and 6 days ago

I think it depends on they keyboard: I haven't had much luck with USB ones.

Although debatable, it should also be REISUB. A program could write data when sent the term signal (as that's a clean shutdown command), and not be synced (which is done first), causing the data to lounge around in cache and then vanish.

Also, it's worth noting that you should wait a second or two between the U and B, just to make sure that everything has in fact been written to disk.

Comment by clockworkavian 373 weeks and 3 days ago

mnemonic for REISUB key combination is ; it is reverse of BUSIER

Comment by alperyilmaz 369 weeks and 4 days ago


This trick will work if and only if you have set some kernel parameter.

Interested guys can find out the parameters and post it here.

Long days before, I was playing with this and not do not remember the parameters but they are most probably in the "kernel hacking" section ( 2.6.21 )

Good Luck....

Comment by Satish 345 weeks and 5 days ago

Your kernel needs CONFIG_MAGIC_SYSRQ=y

Comment by hfs 341 weeks and 4 days ago

I pressed

<alt> + <print screen> + <r>

and my computer went into an infinite loop of opening the print screen dialog. WTF?

Comment by csmeder 329 weeks and 6 days ago

it worked for me after i launched otherwise when doing prntscrn i get screenshot window. it not useful when freezing since unless you are in the tty. ubuntu 10.4

Comment by firstohit 302 weeks and 5 days ago

Lovely! I keep a printed version of the Wikipedia article in my desks drawer.

Comment by jjj0978yug 276 weeks and 5 days ago

Here is how you do it on Fedora


Comment by tevans 130 weeks and 3 days ago

Your point of view

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