Archives For flatpak

This simple tutorial is going to show you how to add both latpak and AppImage package format support, while Ubuntu does not support them out-of-the-box.

Enable Flatpak Support in Ubuntu

Ubuntu is focusing on the native deb and snap support. The developer team has officially announced that they won’t support Flatpak out-of-the-box.

However, user has the freedom of choice to use any other source sources, including Flatpak.

1. To enable Flatpak support, first press Ctrl+Alt+T on keyboard to open terminal, and run command:

sudo apt install flatpak

Type user password (no asterisk feedback) when it asks and hit Enter. In case the command does not work, run sudo apt update first to update package index.

2. (Optional) Then, you can choose to add the Flathub repository, the standard repository that contains tons of applications as Flatpak. To do so, run command:

flatpak remote-add --if-not-exists flathub

When done, log out and back in to apply the variable environment change.

3. Finally, you can either go to and install any Flatpak application, by running the flatpak install command in bottom of its web-page.

Or, install a local .flatpak (or .flatpakref) file by running command:

flatpak install ~/Downloads/file_name_here.flatpak

Enable AppImage Support in Ubuntu

AppImage is a non-install package format for Linux. Like some .exe or .msi files, user can directly click run .AppImage file to launch applications. Though, the ‘allow executing file as program’ option has to be enabled first in file ‘Properties’ dialog.

Ubuntu does NOT support AppImage out-of-the-box, due to switch to fuse3, while the file format requires the classic fuse2.

So enable AppImage is also easy. Just open terminal (Ctrl+Alt+T) and run command to install the fuse2 library:

sudo apt install libfuse2

After that, right-click on your AppImage file and click ‘Run’ to launch the application after enabled ‘allow executing file as program’ and enjoy!

More and more apps today publish Linux packages as Flatpak. Though the run-time libraries take hundreds of megabytes disk space, some apps are really good and useful.

If you have some apps installed as Flatpak in Ubuntu or other Linux like me, then Flatseal may be useful to protect your privacy by managing permissions in per app basis.

Flatseal is a stylish GNOME app that displays all the installed Flatpak apps in the left pane. By selecting an app, it displays the basic information as well as permissions with toggle buttons. The app has an adaptive UI that works great on small screen size, e.g., Linux Phone.

With Flatseal, you may configure following permissions for your Flatpak apps:

  • Network access.
  • Sound server access.
  • GPU acceleration to reduce CPU usage.
  • System file or user file access.
  • Send notifications.
  • System bus and session bus.
  • Print system, smart card, webcam, bluetooth access, and more.

Note: some options (e.g., inter-process communications and X11/Wayland windowing system) may be required for the app to work. Switching those options off may cause function issues, though you may reset them easily afterwards.

As some options are not easy to understand, you may press F1 on keyboard to bring up the ‘help‘ window, which contains the descriptions for each toggle option. And, if permissions are removed and somehow no longer possible to reset, run command below (press Ctrl+Alt+T in Ubuntu to open terminal) to clear the changes and restart Flatseal.

rm ~/.local/share/flatpak/overrides/com.github.tchx84.Flatseal

How to install Flatseal in Ubuntu Linux:

The app itself is available to install as Flatpak package. To try it out, you must have already installed some apps as Flatpak. If not, you need to install the daemon first. For Ubuntu/Debian based systems, simply open terminal and run command:

sudo apt install flatpak

Next, install the Flatseal by running command in terminal:

flatpak install

Or use the command below if you already added the Flathub repository:

flatpak install flathub com.github.tchx84.Flatseal

As you see in picture, the app itself is about 683 KB, while run-time libraries take more than 700 MB. The run-times (e.g., GNOME platform) are shared libraries though that can be used for other Flatpak apps.

Uninstall Flatseal:

To remove the app, simply run command in terminal:

flatpak uninstall --delete-data com.github.tchx84.Flatseal

Note: removing Flatseal won’t reset the permission changes you made for the flatpak apps. You have to manually clear the config files under “~/.local/share/flatpak/overrides” directory to restore them.

Using Flatpak apps in Linux? You may found that Flatpak app appearance does not change when toggling light & dark mode or switching to another app theme.

As more and more apps publish Linux packages via Flatpak, I have a few of them installed in my Ubuntu laptop. However, the apps stick to the light theme whenever I switches to dark mode in Appearance settings.

Since Flatpak runs in sandbox and does not have permission to access the “/usr” directory, it does not use system theme according to the document. So, some popular GTK themes are packaged as Flatpaks. And, it detects the current system app theme and tries to install the Flatpak version of the theme if available during app installation or update.

I’m working with default Yaru theme in the most time, so it automatically installs Yaru theme flatpak package but leaves Yaru Dark not installed. When I switching to Yaru Dark, it can’t find the match theme so falls back to the default Adwaita.

Install GTK Themes in Flatpak:

As all I said, the solution is install the themes you use as Flatpak packages.

For Ubuntu 20.04 and higher that use the default Yaru app theme, press Ctrl+Alt+T on keyboard to open terminal and run command:

  • Install the Dark theme by running command:
    flatpak install flathub org.gtk.Gtk3theme.Yaru-dark
  • Or install the light theme if not exist via command:
    flatpak install flathub org.gtk.Gtk3theme.Yaru-light

There are also elementary stylesheet, Deepin GTK theme, Linux Mint’s Mint-Y in different colors, Arc, Numix, and other themes in Flatpak package format. You can find more themes via command:

flatpak search gtk3theme

Then install your prefer theme via “flatpak install flathub app-id” command.

After that, change app theme via Gnome Tweaks or System Settings to see the magic!

Make theme working for Qt apps:

Though I don’t have Qt applications as Flatpaks, according to the document, you need to open terminal and run following commands one by one to install the required runtime libraries:

flatpak install org.kde.KStyle.Adwaita
flatpak install org.kde.PlatformTheme.QGnomePlatform

That’s all. Enjoy!

This simple tutorial shows how to search for, install, remove, and manager Flatpak apps in Ubuntu Linux.

Flatpak is an universal Linux package format developed by an independent community. Like snap, it runs in sandbox and bundles most runtime libraries.

Flatpak is supported out-of-the-box in many Linux Distros, e.g., CentOS, Fedora, Linux Mint. And it’s available in the most Linux repositories. Since many software developers publish binary packages via flatpak, it’s a good choice to install external apps in Ubuntu Linux.

1. Install Flatpak daemon in Ubuntu:

Unlike Snap, the flatpak daemon is not pre-installed in Ubuntu. You have to first open terminal (Ctrl+Alt+T) and run command to install it:

sudo apt install flatpak

For Ubuntu 18.04, you have to first add this PPA repository before running this command.

Then add the flathub repository via command:

flatpak remote-add --if-not-exists flathub

2. Find for Flatpak App in Ubuntu: is the de facto standard for getting applications packaged with Flatpak. You can browse flatpak apps directly in the web browser via the link below:

If you use Gnome Software instead of Snap Store in Ubuntu, installing gnome-software-plugin-flatpak package will make Flatpak apps available in Software Center.

As well, you can search for an app via flatpak search TEXT. For instance, searching for an radio app via command:

flatpak search radio

NOTE the first time running this command takes quite a few seconds to update database.

3. Install Flatpak package:

If you find an app using the web page, then there are 3 ways to install it in Ubuntu.

Option 1. Click on the “INSTALL” button to download the installer file. Then open terminal (Ctrl+Alt+T) and run command to install it:

flatpak install /PATH/TO/FILE

Since downloaded files mostly save to Downloads folder. Type ~/Downloads/ and hit TAB key twice will show you available flatpak files.

In the case, the command can be:

flatpak install ~/Downloads/com.spotify.Client.flatpakref

Option 2. You can also right-click on “INSTALL” button and copy the URL link. Then install the app via command:

NOTE: It’s NOT the page url, but the install link url.

flatpak install URL

In the case, the command will be:

flatpak install

Option 3. In each app page, scroll down! You’ll find the command line instructions.

If you found an app use flatpak search command, copy the App ID, then install it via:

flatpak install flathub App-ID

In the case the command can be:

flatpak install flathub com.spotify.Client

4. List installed flatpak apps:

For all the installed apps, you can simply run command to list them all:

flatpak list

To make it clean, only list apps via command:

flatpak list --app

And you can list installed runtime libraries, e.g., GNOME, KDE, QT platforms, via command:

flatpak list --runtime

5. Uninstall a flatpak package:

To remove a flatpak, you need to firstly get the App-ID via the previous steps. Then run command:

flatpak uninstall --delete-data App-ID

For instance, remove GIMP as the previous picture shows via command:

flatpak uninstall --delete-data org.gimp.GIMP

Removing flatpak apps WILL NOT remove the independent runtime libraries (QT, GNOME platforms, etc). You can run this command to get rid of them to free up disk space:

flatpak uninstall --unused

And to remove everything your installed, run:

flatpak uninstall --all

In addition for managing flatpak app permissions, try Flatseal.

KDE Plasma 5.12

For those who to install KDE’s Elisa music player, the official flatpak (containerised software package) is available for most Linux desktops including Ubuntu 18.04 and Ubuntu 16.04.

Elisa is a music player developed by the KDE community that strives to be simple and nice to use. We also recognize that we need a flexible product to account for the different workflows and use-cases of our users.

We focus on a very good integration with the Plasma desktop of the KDE community without compromising the support for other platforms (other Linux desktop environments, Windows and Android).

We are creating a reliable product that is a joy to use and respects our users privacy. As such, we will prefer to support online services where users are in control of their data.

How to Install Elisa player in Ubuntu via Flatpak

Open terminal either via Ctrl+Alt+T keyboard shortcut or by searching for ‘terminal’ from application launcher. When it opens, run following commands one by one:

1. First install Flatpak framework if not exist (For Ubuntu 16.04, add the PPA first):

sudo apt-get install flatpak

2. Then add the flathub repository:

flatpak remote-add --if-not-exists flathub

3. Finally install the Elisa music player:

flatpak install flathub org.kde.elisa

Once successfully installed, open the music player from application launcher and enjoy!


To remove the Flatpak package, simply run command in terminal:

flatpak uninstall org.kde.elisa

You may also remove the KDE platform runtime (sandboxed) via command:

flatpak uninstall org.kde.Platform