Ubuntu Icon Themes

Introduction

Icon themes are collections of graphical elements that replace the default system icons in Ubuntu. They provide a consistent visual language across applications, folders, and system elements, allowing you to personalize your desktop experience. Ubuntu's icon theming system is highly flexible, enabling you to install pre-made themes or create your own custom icon sets.

This guide will walk you through understanding, installing, and even creating your own Ubuntu icon themes.

Understanding Icon Themes in Ubuntu

Icon themes in Ubuntu follow a standardized structure defined by the freedesktop.org Icon Theme Specification. These themes provide icons for:

• Applications (Firefox, Terminal, etc.)
• Actions (save, print, edit, etc.)
• Status indicators (battery, network, etc.)
• Places (home folder, desktop, etc.)
• File types (document, image, video, etc.)
• Devices (hard drive, USB, etc.)

Ubuntu's default icon theme is called "Yaru," which provides the orange and purple aesthetic you see after a fresh installation.

Installing New Icon Themes

You can install icon themes in Ubuntu using multiple methods:

Method 1: Using the Ubuntu Software Center

1. Open Ubuntu Software Center
2. Search for "icon themes"
3. Browse the available options and click "Install" on your preferred theme

Method 2: Using the apt Package Manager

Many icon themes are available in Ubuntu's repositories:

bash

# Install Papirus icon theme - one of the most popular themes
sudo apt install papirus-icon-theme

# Install elementary icons
sudo apt install elementary-icon-theme

# Install Numix icon theme
sudo apt install numix-icon-theme

Method 3: Manual Installation

For themes not available in the repositories:

1. Download the icon theme (typically as a .tar.gz or .zip file)
2. Extract the theme to either:
   • System-wide location: /usr/share/icons/
   • User-specific location: ~/.local/share/icons/ or ~/.icons/

bash

# Example: Download and install Tela icon theme
mkdir -p ~/.local/share/icons
cd /tmp
wget https://github.com/vinceliuice/Tela-icon-theme/archive/refs/heads/master.zip
unzip master.zip
cd Tela-icon-theme-master
./install.sh -d ~/.local/share/icons

Applying Icon Themes

Once installed, you can apply an icon theme using:

Using GNOME Tweaks

1. Install GNOME Tweaks if not already installed:

bash

sudo apt install gnome-tweaks

2. Open GNOME Tweaks
3. Navigate to the "Appearance" tab
4. Select your preferred icon theme from the "Icons" dropdown menu

Using gsettings Command

You can also change the icon theme via the terminal:

bash

# List available icon themes
ls /usr/share/icons ~/.local/share/icons ~/.icons 2>/dev/null

# Set the icon theme (replace "Papirus" with your theme name)
gsettings set org.gnome.desktop.interface icon-theme "Papirus"

Icon Theme Structure

If you're interested in creating your own icon theme or modifying an existing one, it's important to understand the standard structure:

ThemeName/
├── index.theme           # Theme metadata
├── 16x16/                # Icons for 16x16 pixel size
│   ├── actions/          # Action icons
│   ├── apps/             # Application icons
│   ├── devices/          # Device icons
│   └── ...
├── 22x22/                # Icons for 22x22 pixel size
│   └── ...
├── 24x24/
│   └── ...
├── 32x32/
│   └── ...
├── 48x48/
│   └── ...
└── scalable/             # Vector icons (SVG format)
    └── ...

The index.theme file defines metadata about the theme:

ini

[Icon Theme]
Name=My Custom Theme
Comment=A beautiful custom icon theme
Inherits=hicolor
Directories=16x16/actions,16x16/apps,...

[16x16/actions]
Size=16
Context=Actions
Type=Fixed

# More directory definitions...

Creating a Simple Custom Icon Theme

Let's create a basic custom icon theme by overriding just a few icons:

1. Create the directory structure:

bash

mkdir -p ~/.local/share/icons/MyCustomTheme/{16x16,22x22,24x24,32x32,48x48,scalable}/apps

2. Create the index.theme file:

bash

cat > ~/.local/share/icons/MyCustomTheme/index.theme << 'EOF'
[Icon Theme]
Name=MyCustomTheme
Comment=My custom Ubuntu icon theme
Inherits=Yaru
Directories=16x16/apps,22x22/apps,24x24/apps,32x32/apps,48x48/apps,scalable/apps

[16x16/apps]
Size=16
Context=Applications
Type=Fixed

[22x22/apps]
Size=22
Context=Applications
Type=Fixed

[24x24/apps]
Size=24
Context=Applications
Type=Fixed

[32x32/apps]
Size=32
Context=Applications
Type=Fixed

[48x48/apps]
Size=48
Context=Applications
Type=Fixed

[scalable/apps]
Size=48
Context=Applications
MinSize=8
MaxSize=512
Type=Scalable
EOF

3. Create or download a custom icon (SVG format is recommended):

bash

# Example: Create a custom terminal icon
# Save this SVG code to a file
cat > ~/.local/share/icons/MyCustomTheme/scalable/apps/terminal.svg << 'EOF'
<svg xmlns="http://www.w3.org/2000/svg" width="48" height="48" viewBox="0 0 48 48">
  <rect width="44" height="34" x="2" y="7" rx="2" ry="2" fill="#333" />
  <path d="M6 15l6 6-6 6" stroke="#3f3" stroke-width="2" fill="none" />
  <path d="M14 27h12" stroke="#3f3" stroke-width="2" />
</svg>
EOF

4. Update the icon cache:

bash

gtk-update-icon-cache -f ~/.local/share/icons/MyCustomTheme

5. Apply your new theme using GNOME Tweaks or gsettings:

bash

gsettings set org.gnome.desktop.interface icon-theme "MyCustomTheme"

Since our theme inherits from Yaru, it will use Yaru icons for everything except the custom terminal icon we created.

Modifying Existing Themes

If you want to modify an existing theme rather than creating one from scratch:

1. Copy the theme to your user directory:

bash

# Example with Papirus
cp -r /usr/share/icons/Papirus ~/.local/share/icons/Papirus-Custom

2. Edit the index.theme file to change the name:

bash

sed -i 's/Name=Papirus/Name=Papirus-Custom/' ~/.local/share/icons/Papirus-Custom/index.theme

3. Replace icons as needed:

bash

# Replace Firefox icon with a custom one
cp my-custom-firefox.svg ~/.local/share/icons/Papirus-Custom/scalable/apps/firefox.svg

4. Update the icon cache and apply the theme.

Advanced: Creating a Complete Icon Theme

Creating a complete icon theme is a significant undertaking, but here are the basic steps:

1. Plan your theme (style, colors, design principles)
2. Create a template icon in SVG format
3. Create the directory structure
4. Create the most common icons first:
   • Apps: firefox, terminal, settings, file-manager
   • Places: folder, home, desktop
   • Actions: save, edit, delete
5. Use symbol links for similar icons
6. Test on different backgrounds and sizes
7. Share your theme with the community

Troubleshooting

Icons Not Showing After Installation

If icons don't appear after installation:

bash

# Update icon cache
sudo gtk-update-icon-cache -f /usr/share/icons/ThemeName
# OR for user themes
gtk-update-icon-cache -f ~/.local/share/icons/ThemeName

# Restart GNOME Shell (in X11 session)
Alt+F2, type "r", press Enter

# Or log out and log back in

Mixed Icons Appearing

If you see a mix of different icon styles:

1. Check the "Inherits" line in your theme's index.theme file
2. Ensure you've created icons for all necessary sizes
3. Check file permissions (should be readable)

Summary

Ubuntu icon themes provide a powerful way to customize your desktop experience. In this guide, we've covered:

• Understanding how icon themes work in Ubuntu
• Installing pre-made icon themes through different methods
• Applying icon themes using GNOME Tweaks and gsettings
• The structure of icon themes
• Creating a simple custom icon theme
• Modifying existing themes
• Troubleshooting common issues

By mastering icon themes, you can create a unique and personalized Ubuntu desktop that reflects your style and preferences.

Additional Resources

• freedesktop.org Icon Theme Specification
• GNOME Human Interface Guidelines
• Inkscape - Free vector graphics editor for creating SVG icons

Exercises

1. Install three different icon themes and compare their styles and completeness.
2. Create a custom folder icon and add it to an existing theme.
3. Design a simple app icon in SVG format and add it to your custom theme.
4. Create a script that switches between different icon themes based on the time of day.
5. Contribute an icon to an open-source icon theme project on GitHub.