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magic sysrq keys + power button

(6 posts) (2 voices)

• Started 11 years ago by llev
• Latest reply from Aleksej
• This topic is not resolved

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1. 

   llev
   

   offline

   Member

   Hi,

   How can I activate the "magic keys" (Alt+SysRq+letter)? They don't work, so I guess they're not active by default.

   Also, I would like the power button to do a shutdown, as it does in some other distributions. Is it possible?

   Thanks a lot.

   Posted 11 years ago #
2. 

   Aleksej
   

   offline

   Coder-hobbyist

   Hi there!

   Magic SysRq key

   1. googling for linux sysrq enable
   2. found Magic SysRq key Wikipedia page
   3. read this:
      

      The feature is controlled both by a compile-time option in the kernel configuration, CONFIG_MAGIC_SYSRQ
      …

   4. search 'SYSRQ' in your own current kernel configuration:
      tux@slitaz:~$ zcat /proc/config.gz | grep 'SYSRQ'
# CONFIG_MAGIC_SYSRQ is not set
tux@slitaz:~$
   5. so, magic key will not work without recompiling the kernel; the end.

   Power button

   1. install xbindkeys package
   2. open terminal, run xbindkeys once to generate default config file ~/.xbindkeysrc (here is hidden file in your home folder)
   3. open SliTaz menu → Settings → Auto started applications → Configuration → add this text to the end of file, save & quit:
      # Fn Keys
xbindkeys &

      Now xbindkeys will start at your every logging on
   4. in terminal:
      xbindkeys -k
      Press your Power button (or any other key that you can associate with any command).
      In my case it shows:
      tux@slitaz:~$ xbindkeys -k
Press combination of keys or/and click under the window.
You can use one of the two lines after "NoCommand"
in $HOME/.xbindkeysrc to bind a key.
"(Scheme function)"
m:0x0 + c:124
XF86PowerOff

   5. open ~/.xbindkeysrc in your preferred text editor:
      nano ~/.xbindkeysrc
or
leafpad ~/.xbindkeysrc
      or open PCManFM, press ‹Ctrl+H› to see hidden files and double click on .xbindkeysrc file
   6. copy last three lines from terminal above into your text editor, do not close text editor (we do not know the command!)
   7. to show logoff/reboot/shutdown menu I press icon on bar, go to /usr/share/applications and search for this icon; right click on it → open in text editor; see command in this line:
      Exec=tazbox logout
      Open comand tazbox logout in terminal. Yes, it works! But if I want only shutdown?
   8. Where is located tazbox script? here is the answer (in /usr/bin/tazbox), open this file in text editor and search for appropriate command
   9. Lines from 291 to 304:
      logout)
# Logout window with actions
main=logout_main
      # Deal with --button values
      case $? in
      1) exit 0 ;;
      *) continue ;;
      esac
      # Deal with $main values
      case "$main" in
      *exit) openbox --exit || jwm -exit ;;
      *reboot) reboot ;;
      *halt) poweroff ;;
      esac ;;

      So, to halt the your computer, you must command poweroff! Ok, ok… Now back to our text editor with .xbindkeysrc (now we know the command)

   10. Final edition:
       
#power off button
"poweroff"
m:0x0 + c:124
XF86PowerOff

   11. That's all! (If you have frugal SliTaz installation then save your system before). Press your Power button to poweroff. Start your machine and press Power button again. All work.

   Posted 11 years ago #
3. 

   llev
   

   offline

   Member

   Hi Aleksej,

   Thanks a lot for your detailed explanation! Alas the power button isn't detected (neither by xev), so I bound poweroff to Ctrl-Alt-Del instead.

   Maybe I'll consider recompiling the kernel. The Sysrq keys are useful to avoid a mere unplugging when the computer is frozen.

   Thanks again.

   Posted 11 years ago #
4. 

   Aleksej
   

   offline

   Coder-hobbyist

   Any response from Power key? No key code & no key name?

   Wikipedia says about SysRq key:

   Some people view this key as giving access to dangerous system-level commands to anyone who has physical access to the keyboard or serial console.

   ;)

   Posted 11 years ago #
5. 

   llev
   

   offline

   Member

   Absolutely nothing. I just noticed that "Power button" is reported in Xorg's log (and it's supposed to be configured!). But I have no idea if something can be put in xorg.conf for it to work.

   Posted 11 years ago #
6. 

   Aleksej
   

   offline

   Coder-hobbyist

   It is good that you can configure your keys using xbindkeys, but it is not right way while we using power/suspend/hibernate keys!
   I want to find right way, and I started here: Shutdown Pressing Power Button - ArchWiki.
   Here is acpi package file list in the SliTaz stable. I have installed acpid package. And opened their files in text editor.

   For example, /etc/acpi/events/buttons:
   # /etc/acpi/event/button
# lid, sleep or power button events
event=button.*
action=/etc/acpi/acpi_handler.sh "%e"

   Start of file /etc/acpi/button.sh:
   #!/bin/sh
# button.sh - Managing button events for SliTaz
#

   source /etc/acpi/key-constants
...

   But we have not file key-constants in any SliTaz package! But button.sh is designed exclusively for SliTaz! Hmm...

   Here is acpid branch in the wok-stable (with receipt and other stuff).
   I found key-constants here. Now my experiments suspended (I close my lid ;) )

   Seems like acpid is broken and have not all parts of its body to work properly...

   Posted 11 years ago #

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