I am unable to find an option to change themes in Ubuntu Linux. How do I install or change themes in Ubuntu 16.04/17.10 Linux?

Ubuntu Tweak is utility software that makes it easy to configure your system and desktop environments for Ubuntu or Gnome based desktop. It works on Ubuntu, Debian, Fedora and other Linux distros. It is a free and open source software. This page shows how to install or change themes in Ubuntu Linux.

Two types of themes

• Shell theme – Stored or installed in ~/.themes/ directory. Shell themes are themes for the shell.
• GTK3 theme – Stored or installed in /usr/share/themes/ directory. GTK3 themes are themes for applications.

Procedure to change theme in Ubuntu

1. Install gnome-tweak-tool by typing: sudo apt install gnome-tweak-tool
2. Install or download additional themes
3. Start gnome-tweak-tool
4. Select Appearance > Themes > Choose theme Applications or Shell from the drop down menu

Let us see all steps in details.

Step 1. Install gnome-tweak-tool

Open the terminal application and type the following apt command/apt-get command:
$ sudo apt update
$ sudo apt install gnome-tweak-tool

I also recommend that you install the following package:
$ sudo apt install gnome-shell-extensions

Step 2. Create directories

To store themes/icon files create the following directories using the mkdir command:
$ mkdir -v ~/.{themes,icons}
mkdir: created directory '/home/vivek/.themes'
mkdir: created directory '/home/vivek/.icons'

Step 3. Install theme on Ubuntu

You can install or search GTK 3 themes using apt command:
$ apt search theme
$ apt search theme | grep arc
$ sudo apt install arc-theme

How to download shell themes

To grab shell themes (or GTK3/2 themes) from the Internet and download it with the wget command:
$ cd ~/.themes/
$ cd /tmp/
$ wget https://github.com/daniruiz/Flat-Remix-GNOME-theme/archive/master.zip
$ unzip master.zip
$ mv flat-remix-gnome-master/Flat-Remix/ ~/.themes/
$ gsettings set org.gnome.shell.extensions.user-theme name "Flat-Remix"

Step 4. How to change theme in Ubuntu 16.04/17.10

Start gnome-tweak-tool by typing the following command:
$ gnome-tweak-tool &

Now all you have to do is click on Appearance > Themes > Applications and select themes from rop down menu.

A note about enabling shell themes

Remember we installed gnome-shell-extensions? You need to use that one to enable shell themes. Start gnome-tweak-tool again:
$ gnome-tweak-tool &
Click on the Extensions &gt Turn on “User themes” option:

Now all you have to do is click on the Appearance > Themes > Application and select shell theme from drop down menu.