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When I press brightness contrast button to reduce and increase the brightness in Ubuntu it is neither showing any brightness bar nor having any effect on brightness.

However, when I manually change my brightness, it is working.

Zanna
  • 72,312
Amit Aslia
  • 1

1 Answers1

1

The file you should fix is named "grub" at this address: Open Nautilus (Files), go to Computer

/etc/default/grub

to edit this you should have root access or just open terminal and run this

sudo -H gedit /etc/default/grub

Check this out: 

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

on the 11th line it says:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

so change it to

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_backlight=vendor"

and then run this command in terminal

sudo update-grub

then it should be fixed after restarting the system.

Sometimes it doesn't work like this, you may like to test the change like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

don't forget to run sudo update-grub and restart

Zanna
  • 72,312
Mirza
  • 351