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Some Lenovo laptops have keyboard backlights, and they can be turned on using Fn + Space. There are three states: off, normal and bright.

When I start Ubuntu, these laptops always default back to a burning sun screen brightness and the keyboard lights off.

I want a medium brightness and keyboard lights on by default, because I usually use this laptop in dark environments.

The backlight is easy. Internet is filled with information about this.
echo 10 > /sys/class/backlight/acpi_video0/brightness

But how do I turn on the keyboard backlights with a command? I've been looking here but it seems to do nothing:
/sys/class/leds/tpacpi\:\:thinklight

Updates

I tried for i in {1..32}; do xset led $i; done but nothing changes. Perhaps the keyboard backlight for Lenovo laptops has a proprietary driver and can only be controlled through tpacpi?

Also tried for i in $(find /sys/devices/platform/thinkpad_acpi/leds/ | grep /brightness\); do echo 255 > $i; done of no avail.

Redsandro
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  • Either `xset led` *(that is almost 100% likely to be Caps Lock, etc, but I'll add it in anyway)* or [`setleds`](http://manpages.ubuntu.com/manpages/lucid/man1/setleds.1.html). **Edit:** Found [this](http://askubuntu.com/questions/13886/how-to-light-up-back-lit-keyboard) – Wilf Nov 28 '13 at 19:32
  • It doesn't work. I tried `for i in {1..32}; do xset led $i; done` but nothing changes. – Redsandro Nov 28 '13 at 23:29
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    Thank you for the Fn-space combo since I could not figure it out for quite some time. – alamar Jul 16 '21 at 21:21

5 Answers5

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This is really needed to be fixed!

I think this is a common bug in new thinkpads. If you light keyboard manually fn + space then executed: 

echo 0 > /sys/class/leds/tpacpi\:\:thinklight/brightness

keyboard will fade out. Please see the following link if it helps:

http://www.spinics.net/lists/ibm-acpi-devel/msg03090.html

rashad
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  • Hey you're right, I didn't know. Since we can turn it off, it 'feels' like it would be a piece of cake to fix this for developers. Is there a bugreport yet? – Redsandro Dec 29 '13 at 16:11
  • The email suggested this workaround: https://gist.github.com/hadess/6847281 Any idea how can we implement it ? – rashad Dec 29 '13 at 17:14
  • Note the "thinklight" is different to the keyboard backlight. Mine does not have a thinklight. – Criggie Sep 21 '22 at 05:59
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Looks as this has been updated, my X1C with ubuntuMATE 16.04 LTS has

/sys/class/leds/tpacpi\:\:kbd_backlight/brightness

which works as expected ie:

# echo 2 > /sys/class/leds/tpacpi\:\:kbd_backlight/brightness

Brings it to full light :)

wuxmedia
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  • Hey, yes indeed! Thanks for taking the time to share this to an old question. :) – Redsandro Jul 26 '16 at 11:56
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    No probs, it was the first hit when I was looking, thought it can't be _that_ hard, so thought I should update this one with my findings :) – wuxmedia Jul 27 '16 at 07:27
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This is the bash script I use:

https://gist.github.com/vzaliva/0adba7bc40e2f31a0b5f802af2a63267

Works on IBM ThinkPad X260 with Ubuntu 16.04.

krokodil
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  • IBM? That laptop has got to be at least 10 years old! But it works on my Carbon X1, too! To be fair, the code from __hadess__ as answered by __rashad__ did the same, but I don't want to take 5 steps and install compilers. I was looking for a simple bash command. And this is something I can use. Thank you for responding to my 3 year old question. Accepted. – Redsandro May 22 '16 at 23:59
  • Glad you found it useful. Of course I have meant Lenovo Thinkpad and my X260 is brand new. I just had the same problem and found this answer, but I did not like C program which also requires manual modprobe, so I re-wrote it as a script. The original C program authors did all heavy-lifting. – krokodil May 23 '16 at 20:52
  • Thank you. Works in 2022 just as good :) – gnzg May 03 '22 at 21:26
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Ok, it works fine with me with this gist:

https://gist.github.com/hadess/6847281

  • First of all download the gist above, I renamed it to ThinkLight.c instead of tmp.c.

  • Make sure you have glib-2.0 installed:

    sudo apt-get install libglib2.0-dev

  • Compile ThinkLight.c as the following:

    gcc -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include ThinkLight.c -o ThinkLight -lglib-2.0

  • Load ec_sys module ( this can be added to /etc/modules on boot ):

    sudo modprobe ec_sys

  • Finally execute ThinkLight with level argument (0, 1, or 2):

     sudo ./ThinkLight 0
 sudo ./ThinkLight 1
 sudo ./ThinkLight 2

Special thanks to hadess for making this happen!

rashad
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  • Any idea how to run this without sudo? Trying to run this within another script, and that runs as my user. – zsquare Jun 21 '15 at 20:13
  • I tried this and got some errors :( ThinkLight.c: In function ‘main’: ThinkLight.c:56:6: warning: implicit declaration of function ‘lseek’ [-Wimplicit-function-declaration] if (lseek (fd, 0xd, SEEK_CUR) < 0) { ^~~~~ ThinkLight.c:60:6: warning: implicit declaration of function ‘write’ [-Wimplicit-function-declaration] if (write (fd, &levels[level], 1) < 0) { ^~~~~ – Heriberto Juarez Jul 02 '19 at 04:58
  • @HeribertoJuarez this is an old answer, you can manipulate this directly with the new Linux kernels. Check wuxmedia's answer – rashad Jul 25 '19 at 20:21
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My T450s would not re-enable keyboard backlight upon resume with kernels older then 4.6. FWIW, with 4.6 now, keyboard backlight is set to the brightness it had before suspend.

bk138
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