If I turn it off via Fn + ->(right arrow) it will stay off until I stop typing. After a while, when I start typing again (wake) it turn on again.
In 22.04 this worked dell - Keyboard backlight keeps going on in Ubuntu 16.04 LTS - Ask Ubuntu
but now that file is empty.
Can someone please help? Thank you.
Have you considered modifying parameters in dconf-editor?
Search for "backlight" gave me
/org/mate/power-manager/backlight-enable
as a possible parameter, but I can't test because my keyboard doesn't have backlight. 
Other than that, you would need to indicate the specifics of the keyboard in question for people to recognize that and respond specifically to your needs.
Hi. I have nothing in
/org/mate/power-manager/backlight-enable
How do I show the specifics of the keyboard?
Acc to dell - Keyboard backlight keeps going on in Ubuntu 16.04 LTS - Ask Ubuntu
in this folder
/sys/devices/platform/dell-laptop/leds/dell\:\:kbd_backlight
there is brightness_hw_changed which holds 0 1 2 3 4 values and max_brightness file which holds the max value (4).
If I turn off the light the value is 0. if I wait and then start typing again, the value is still 0 but the keyboard lights up.
Update there si another file called brightness that holds 4 when the above happens. That is updated manually the same time the brightness_hw_changed file is updated but on wake it is updated independently of brightness_hw_changed.
this worked... dell - Keyboard backlight keeps going on in Ubuntu 16.04 LTS - Ask Ubuntu . The keyboard just blinks and it turns off again on wake on AC. Same on battery.
Hi @marius-ciclistu,
What I provided was not a filesystem path. It was the kernel parameter tree that is edited by dconf-editor. If you open that tool, it will give you the option to look at various system settings (VERY dangerous territory) and let you change those to what might better suit your context.
As I said, open dconf-editor and do a search for "backlight", and see which parameters are displayed for you.
Those will likely include the same ones you ended up modifying via a different command-line method, but what you did modified the parameters that are visible and modifiable in dconf-editor.
dconf-editor is the more general method of trying to track down what might be relevant to your problem, whatever that might be, if you have an inkling of the correct wording that the system developers used to name the parameters in question. To identify what that wording would be, a first attempt at searching various fora on the topic will provide answers by experts which, while they may not solve a problem, will use the proper/correct terminology which you can then use for searching in dconf-editor.
Hope that helps for the future! 