mjhjmtu

My screen is just too bright. How can I adjust screen brightness? So far I tried the following:

1. "Brightness and lock" settings doesn't work.


2. Fn + F6 or F7 doesn't work.


3. 
   This doesn't work.


4. 
   This doesn't work too.

My Laptop is Toshiba Satelite L745

You can try xrandr tool.

First run xrandr --verbose and look for a line with resolution like LVDS1 connected 1024x600+0+0. The name of your display (LVDS1 in this example) is needed here. Now you are ready to set brightness:

xrandr --output LVDS1 --brightness 0.4

xrandr sets software, not hardware brightness so you can exceed both upper and lower limits:

xrandr --output LVDS1 --brightness 1.7
xrandr --output LVDS1 --brightness -0.4 #negative value is also possible
xrandr --output LVDS1 --brightness 1

I found the screen brightness solution in a somewhat obscure article. My issue was my laptop couldn't remember brightness settings upon reboot. I'll post the link at the end of my answer.

All that was needed was to edit the file /etc/rc.local and add one line.

First, back up the rc.local file. 
If something goes wrong you can revert to the original file.

cat /etc/rc.local

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# screen brightness line added
# it's to make the laptop remember settings at power up.

echo 7 > /sys/class/backlight/acpi_video0/brightness

exit 0

Note that I added the line
echo 7 > /sys/class/backlight/acpi_video0/brightness to my rc.local file.

In my Debian Wheezy setup, the value echo 7 > … sets brightness midway between dark and bright. So 7 is perfect for me. Choose a value that suits you.

rc.local runs when you restart your machine.

Here's the link:
Installing Ubuntu on Samsung 5 (SSD+HDD) | LinuxMeerkat

Scroll down the page to find how to change default screen brightness on a laptop.

For me on Acer 7530G with:

Distributor ID: Debian
Description: Debian GNU/Linux 8.6 (jessie)
Release: 8.6 Codename: jessie

The solution was in Application Menu> Settings> xfce4-desktop there can you set the brightness of the monitor, for me was 100 fine.

Before doing this, I installed firmware-linux-nonfree; I don't know whether that's affected anything.

If xbrightness does not detect the backlight, you'll need to find the backlight file and manually set the backlight value yourself. Here's the process I used for my Toshiba Satellite C50-B-14Z:

wizzwizz4@mylaptop:~$ ls /sys/class/
ata_device devfreq i2c-adapter net scsi_device vc
ata_link dma ieee80211 pci_bus scsi_disk video4linux
ata_port dmi input phy scsi_generic vtconsole
backlight drm iommu powercap scsi_host watchdog
bdi firmware leds power_supply sound wmi
block gpio mem ppdev spi_master
bluetooth graphics memstick_host printer thermal
bsg hidraw misc rfkill tpm
devcoredump hwmon mmc_host rtc tty
wizzwizz4@mylaptop:~$ ls /sys/class/backlight/
intel_backlight
wizzwizz4@mylaptop:~$ ls /sys/class/backlight/intel_backlight/
actual_brightness brightness max_brightness subsystem uevent
bl_power device power type

Now I've got the brightness file: /sys/class/backlight/intel_backlight/. I can read the value of this file:

wizzwizz4@mylaptop:~$ cat /sys/class/backlight/intel_backlight/brightness
3754

This suggests that it's a 16-bit value, as opposed to the usual 4-bit. I like it quite dim, so I'll set it to 390 out of 65535:

wizzwizz4@mylaptop:~$ echo 390 | sudo tee /sys/class/backlight/intel_backlight/brightness
390

And the screen dimmed! Yay!