[systemd-devel] CtrlAltDelBurstAction

[Mantas Mikulėnas]

On Sun, Aug 5, 2018 at 6:21 PM Reindl Harald <h.reindl at thelounge.net> wrote:

> CtrlAltDelBurstAction=
> Defines what action will be performed if user presses Ctrl-Alt-Delete
> more than 7 times in 2s. Can be set to "reboot-force", "poweroff-force",
> "reboot-immediate", "poweroff-immediate" or disabled with "none".
> Defaults to "reboot-force"
>
> [root at srv-rhsoft:~]$ 7~7~
>
> 7~7~7~7~7~7~7~7~5~7~5~5~5~5~5~5~5~7~5~5~7~5~5~5~5~5~5~7~7~7~7~7~5~7~7~5~5~7~5~7~7~7~3~3~5~5~7~5~7~7~
>
> i guess the number appearing in my console is the required key hits
>

Those are ANSI-style escape codes that your shell doesn't know how to
interpret and gives up midway. Specifically, \e[3~ is Delete, \e[5~ is
PageUp, \e[7~ is... not even in the default Linux keymap at all, although
it's the Home key in urxvt.

when i keep holding CTRL+ALT and repeatly press DEL it keeps at seven
> and for the whole keyboard-combination from scratch i am not phyiscally
> made the way it needs to get recognized
>

As far as I know, systemd does not read any keypresses to begin with. For
Ctrl-Alt-Del to work, your console has to be in xlate (non-raw) mode, the
console keymap has to map the scancode to "Boot", which causes the kernel
to send SIGINT to pid 1, and that's the "Ctrl-Alt-Del was pressed"
indication that all inits use.

So if you're sitting at the actual console, then use Alt-SysRq-R to fix the
keyboard mode, and make sure a non-garbage console keymap is loaded.

And if you're doing this over serial, that doesn't appear to understand
Ctrl-Alt-Del at all. According to internets, the serial "break" signal is
supposed to do possibly the same thing, or at least something similar (like
Alt-SysRq).

-- 
Mantas Mikulėnas
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