Re: [gentoo-user] Re: How to poweroff the system from user?

[Fernando Rodriguez <frodriguez.developer@outlook.com>]

On Sunday, March 29, 2015 12:23:00 PM lee wrote:
> Philip Webb <purslow@ca.inter.net> writes:
> What's the last time you pressed Ctrl+Alt+Del and it actually worked?
> It's a legacy thing from times when freezes/crashes were common and when
> it did work and was useful.
> 
> Nowadays, when you're pressing it, usually nothing happens anyway
> because the machine is down to where you have to press the reset button
> or to turn off the power (if you can't log in with ssh).  When the
> machine still works, Ctrl+Alt+Del also works, which means that the
> default does nothing but create a security hole.

On Linux now there's the Magic SysRq Key feature for that. If enabled (I think 
it is by default, may be wrong) you can use ctrl-alt-sysrq plus one these keys 
even if your kernel panics or freezes in most cases (ctrl may only be needed 
from xorg):

r - to get the keyboard back so you can switch to VT if xorg freezes
e - to terminate all processes gracefully (SIGTERM) except pid 1
i - to terminate all processes forcefully (SIGKILL) except pid 1
s - to sync all filesystems 
u - to unmount them and remount readonly
b - to reboot

Easy to remember as "Reboot Even If System Utterly Broken"
There's a lot of other commands in the kernel docs sysrq.txt
 
> So how can we have this default changed?

Somebody posted that on this very thread. Replace the ctrlaltdel entry on 
inittab with /bin/false.

-- 
Fernando Rodriguez