Ubuntu: adjust brightness with the Fn keys

In the previous article, we have seen how to install Bumblebee to take full advantage of the Optimus technology of NVIDIA graphics cards, but we have also exposed the problem of brightness that is impossible to adjust in any way .. or almost.

In my case I could not control the brightness through the keyboard shortcuts, that is the Fn keys, nor from the system settings and therefore this remained at the maximum making the PC unusable. To make it work, I looked for solutions that enabled convenient keyboard shortcuts and, in addition to many non-working applications, I found a way to enable you through a small modification of a file, the grub.

The solution is easy and fast! Open the terminal and type the following command line to edit the file

sudo nano /etc/default/grub

then we replace the line




GRUB_CMDLINE_LINUX_DEFAULT = "quiet splash acpi_osi ="


UPDATE: It is also possible to modify the following line instead of the previous one (Thanks to Roberto):

GRUB_CMDLINE_LINUX = "quiet splash acpi_osi = Linux acpi_backlight = vendor"

and save the file with Ctrl + O e Ctrl + X to terminate the file, then update the grub

sudo update-grub

and restart the PC.

At the start it will finally be possible to control the brightness of the screen directly from the keyboard, but it is still impossible to do so from the system settings (at least for me) but at least we have found a way to adjust it! Unfortunately, even the brightness indicator is no longer shown after this operation, but it is only something graphic that, even if it was first shown, had no practical function.


The tests were done on an Acer Aspire 5755G

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