[Bglug] Something i learned today ...

[Peter]

There is magic on the keyboard - incarnated in the SysRq (i think this 
stands for system request, long thought to be a holdover from the 
begining of time).
You can use it, along with others to get messages to the kernel, if it 
hasn't panicked; for example when GoogleEarth locks up the X-Server and 
your screen transitions from the desert of Nevada to all black as just 
happened to me.

Using the key combination Alt + SysRq, and while holding these keys 
down, press these keys in sequence with a delay of several seconds 
between each key press  r  e  i  s  b


              "Cleanly Restarting Your System

        Used in sequence, some of these actions can be used to cleanly
        end processes, flush data to disk, unmount all file systems, and
        restart your computer. To perform this process, press and hold
        the Alt + SysRq key combination and – while holding the Alt and
        SysRq keys down — type the following keys in order, pausing for
        several seconds in between each key:

            *reisub*

        The mnemonic “*R*aising *E*lephants *I*s *S*o *U*tterly
        *B*oring” is often used to remember this sequence. Here’s what
        each key does:

          * *r* – Puts the keyboard into raw mode, taking control of it
            away from the X server.
          * *e* – Sends the terminate signal to all processes, asking
            them to end gracefully.
          * *i* – Sends the kill signal to all processes, forcing them
            to end immediately.
          * *s* – Flushes data from your cache to disk.
          * *u* – Remounts all file systems read-only.
          * *b* – Reboots your computer.

        "


Here is the link to the full document of Alt+SysRq's many charms and spells:

https://www.kernel.org/doc/Documentation/sysrq.txt

There's always something new to discover!

Peter Richards

-- 
Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe. -  Albert Einstein

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