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I'm using a Vsphere client on Windows XP over a VNC link (Vinagre) from an Ubuntu 10.10 desktop running WindowMaker. It all works pretty well, but I can't find any way to press the Magic SysReq key (used to reset Linux hard). Neither Vinagre nor Vsphere has any sort of keyboard that can be pressed; trying to use the SysReq key just results in the local system being reset. Running Vinagre in full screen makes no difference.

How do I press SysReq in this combination of software? I thought that sending a BRK would help, but there's no way to do that either. I thought PrScr would do it, but don't know how. Switching from Vinagre to xtightvncviewer didn't help at all.

Am I missing something or is sending a SysReq just not possible?

UPDATE: I found information about /proc/sys/kernel/sysrq-key (which allows you to specify the key) but that seems to have been removed sometime during the Red Hat Enterprise Linux 5.x kernel lifetime. This was a feature in the mainline kernel at one time.

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this could maybe help you:… – dnozay Feb 18 '14 at 19:14

sysrq on ESXi VNC/Console for a redhat/fedora/debian guest:

[ctrl+alt] (keep them pressed all the time) + [space] + <release [space]> + [PrintScrn] + <sysrq> + <release [ctrl+alt]>

you might also want to try [break] instead of [printscrn]

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This looks like the best option for the Console itself, but with VNC not sure this could work... but will try next time I get a chance. – Mei May 23 '14 at 20:43

Not sure if it helps in your situation (won't help if the kernel is in panic) but there is a file /proc/sysrq-trigger:

Using the echo command to write to this file, a remote root user can execute most System Request Key commands remotely as if at the local terminal. quote

A list of letters to echo to this file can be found for example here

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The problem I've been seeing is an apparent lockup: so this won't help - at least not from a local shell. I'm leery of making such a capability available via the network without security precautions. – Mei Feb 3 '12 at 16:05

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