How to change brightness on CRT display through the Linux command line?

Solution 1:

Look under /sys/class/backlight for the appropriate files to frob.

echo -n 6 > /sys/class/backlight/acpi_video0/brightness

Solution 2:

$ sudo apt-get install xbacklight

How to set brightness to 50%

$ xbacklight -set 50

How to increase brightness 10%

$ xbacklight -inc 10

How to decrease brightness 10%

$ xbacklight -dec 10

More info here

Solution 3:

You need to control the monitor over DDC. See http://ddccontrol.sourceforge.net/ for one program that lets you do this.

Solution 4:

If you don't have hardware support for changing the brightness of your monitor you could use the command xrandr together with its option flags --output and --brightness, as can be seen in my answer to a similar question on askubuntu.com

Solution 5:

You could give this solution a try:

echo -n 100 > /proc/acpi/video/VGA/LCD/brightness

Also, in the comments, there are some hints what to do alternatively if it doesn't work (f.e. using GLX0 instead of VGA.

EDIT: As this doesn't seem to help, another user in the comments suggests to install xbacklight and calling xbacklight -set 100.

EDIT2: And another one says if you don't have a video folder, try sudo modprobe video.