When I switch to a console by Ctrl-Alt-F1, the screen becomes darker than in Ctrl-Alt-F7.
So I wonder how to adjust brightness in command line without reboot? My Ubuntu is 14.04 on Thinkpad T400 laptop.
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2 Answers
You can adjust your brightness using the following command:
echo 7 | sudo tee /sys/class/backlight/acpi_video0/brightness
The maximum value is available with:
$ cat /sys/class/backlight/acpi_video0/max_brightness
15
You may have to find the right device (here mine was acpi_video0 but you can also have intel_backlight).
answered Apr 1, 2015 at 8:03
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Thanks. How can you make the change of brightness take effect immediately?– TimApr 1, 2015 at 10:36
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@Tim The command changes the brightness immediately. I guess that you need such command to be executed when you enter the console? Again I think this should be handled by some config/startup script. So could you please clarify? Thanks Apr 1, 2015 at 11:08
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Yes. when I enter the console by ctrl-alt-F1, can
echo 7 | sudo tee /sys/class/backlight/acpi_video0/brightnesschange the brightness immediately?– TimApr 1, 2015 at 11:17
xrandr -q | grep " connected"
Type that to find out the first block of text it spits out, which is your display.
Use that with the next command:
xrandr --output VGA1 --brightness 0.7
Go get it back to original brightness:
xrandr --output VGA1 --brightness 1
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Thanks. (1) All the commands can't run in a text console. The error is
Can't open display. They can run in graphical console (i.e. Ctrl-Alt-F7). (2) How can I check the current brightness in either a text or a graphicl console?– TimApr 1, 2015 at 2:58