Ttgjyuk

Honestly I like working in a dark environment (Twilight on my all my editors), and recently I switched from a Windows to Linux (Ubuntu 16.04 with Unity Desktop on a PC). And being a night worker the brightness is a little harmful to my eyes.

I searched for a bit and these were some of the commands I have tried so far after realizing that the GUI is just not giving me what I need - A Dimmer Screen.

$ dconf-editor

A snap of the values of the dconf-editor.

$ add-apt-repository ppa:indicator-brightness/ppa
$ apt-get update
$ apt-get install indicator-brightness

Nothing happened after toggling the new indicator.

$ apt-get install xbacklight
$ xbacklight -set 40
$ xbacklight -set 20

Enabled Xbacklight at startup

$ ls /sys/class/backlight/

acpi_video0

I dont seem to have intel_backlight so I didn't do this last hack on my system.

$ gedit /etc/rc.local
echo 900 > /sys/class/backlight/intel_backlight/brightness

I am a little lost. I would like to know if there is any tool that I can use to decrease the brightness on the system as a whole besides this or is there something that I am missing as a Noob user?

I use Screen Dimmer for Firefox, Twilight for my Code Editors and the terminal is already black. It is the window applications like the File Viewer, Libre Office etc that needs to be dimmed down. I would consider getting a darker desktop theme also (if that is possible) as a valid answer.

Thank-you for being patient enough to read through this rather unintentionally long question.

You should've tried f.lux, a tool that will change the color temperature of your computer’s display depending on the time of day. Quote from f.lux
page:

f.lux makes your computer screen look like the room you're in, all the time. When the sun sets, it makes your computer look like your indoor lights. In the morning, it makes things look like sunlight again.

Tell f.lux what kind of lighting you have, and where you live. Then
forget about it. f.lux will do the rest, automatically.

To install flux, press Ctrl+Alt+T to launch terminal and type:

sudo add-apt-repository ppa:nathan-renniewaldock/flux
sudo apt-get update
sudo apt-get install fluxgui

If you don't want add ppa, but prefer .deb file:

wget https://launchpad.net/~nathan-renniewaldock/+archive/ubuntu/flux/+files/fluxgui_1.1.9~20161125-g43350e0-1~xenial_all.deb
sudo apt install ~/Downloads/fluxgui_1.1.9~20161125-g43350e0-1~xenial_all.deb

Note: f.lux require your location to retrieve Latitude and Longitude, so make sure fill them (longitude is optional) to get it work.

Redshift is easy to install, and even easier to use. Just open a terminal and do sudo apt-get install redshift redshift-gtk. Once the installation is complete, click the Dash icon, type 'red' (without quotes), and click the Redshift icon. The software does the rest. Here is a link to a page with a very good introduction to redshift. (not my work) http://jonls.dk/redshift/

Try Ubuntu 17.04. It has Night Light under display settings. btw I use GNOME based.

There are two packages already in the distribution for adjusting brightness for working at night.

Those are redshift that does the work and redshift-gtk that sits in the indicator area.

Install redshift using

sudo apt-get install redshift redshift-gtk

Then you can access the temperature of your display using redshift -O 5500 in the terminal or you can just run redshift and it will automatically adjust the brightness and temperature according to your location and time of day.

The redshift can also be accessed from the indicator bar using redshift-gtk.

The temperature parameter of redshift takes input from 1000 to 25000, thats a pretty long range and will cater to all your uses. Just for reference normal screen uses 6500K temperature. So for reading mode you can set it to around 5500+.

Although you can also use redshift -x instead of setting temperature 6500.

You can set your preferred defaults for day and night using redshift -b DAY:NIGHT and then redshift -b 1.0:0.75.

It also allows you to set your custom location using -l tag.

Check out this link to see how to add it to autostart:
https://www.maketecheasier.com/protect-eyes-redshift-linux/