Flatpak

cache22 ships flatpak in all variants. Desktop variants additionally include a graphical storefront for browsing and installing apps: KDE Discover on the kde variants, GNOME Software on the gnome and hyprland variants.

Flatpak is the recommended way to install GUI applications on cache22. The applications run in their own sandboxed environments, do not modify /usr, and update independently of the OS image.

Installing an app

Via the storefront (desktop variants): launch Discover or GNOME Software from the application menu, search, click Install.

Via the command line:

flatpak install flathub org.mozilla.firefox
flatpak install flathub com.discordapp.Discord
flatpak install flathub org.libreoffice.LibreOffice

The first install per Flathub remote prompts to add the remote. cache22’s Flathub configuration is preinstalled; the prompt should not appear.

To install for the system (all users) instead of the current user:

sudo flatpak install --system flathub org.mozilla.firefox

Default install location is per-user (~/.local/share/flatpak/). System-wide installs go to /var/lib/flatpak/.

Listing and updating

flatpak list                       # All installed apps + runtimes.
flatpak list --app                 # Apps only.
flatpak update                     # Update all installed apps + runtimes.
flatpak update org.mozilla.firefox # Update one app.

cache22-update --app-updates runs flatpak update -y for the user who invoked sudo, in addition to the OS update.

Running

flatpak run org.mozilla.firefox

Or use the desktop entry that flatpak installs in the application menu.

Removing

flatpak uninstall org.mozilla.firefox
flatpak uninstall --unused          # Remove unused runtimes.

Sandbox permissions

Each Flatpak app declares the sandbox permissions it needs (filesystem access, network, devices). To inspect what an app has access to:

flatpak info --show-permissions org.mozilla.firefox

To override permissions per-app:

flatpak override --user --filesystem=home org.mozilla.firefox       # Grant home access.
flatpak override --user --nosocket=wayland org.mozilla.firefox      # Block Wayland (force XWayland).
flatpak override --user --reset org.mozilla.firefox                 # Reset overrides.

System-wide overrides use --system instead of --user and require root.

For GUI inspection of permissions, Flatseal (also a Flatpak) provides a per-app permissions editor.

Other remotes

Flathub is the only remote configured by default. To add others:

flatpak remote-add --if-not-exists <name> <url>

Common alternatives:

GNOME Nightly.
KDE Nightly.
Vendor-specific remotes (some apps publish their own).

Graphical storefront (desktop variants)

The kde variants ship KDE Discover. The gnome and hyprland variants ship GNOME Software. Both provide the same basic functions:

Browse Flathub by category.
Search apps.
See app screenshots, descriptions, and ratings.
Install / update / uninstall.

Launch either from the application menu.

Neither can alter the base image. GNOME Software is built with its PackageKit backend disabled. Discover has that backend compiled in, but cache22 does not install the packagekit daemon it needs, so it stays inactive. Both are left managing Flatpaks and firmware updates only.

When to use Flatpak vs Distrobox vs usroverlay

Use case	Best tool
GUI desktop apps (Firefox, Discord, LibreOffice, etc.)	Flatpak
CLI tools, dev environments, AUR packages	Distrobox
Testing a one-off `pacman -S` change to cache22 itself	usroverlay (discarded on reboot)
Permanent additions to cache22	Fork the repo

What about .rpm, .deb, .exe files

KDE variants of cache22 register cache22-foreign-pkg as the default handler for application/x-rpm, application/vnd.debian.binary-package, and application/x-ms-dos-executable. Double-clicking a downloaded .rpm, .deb, .exe, or .msi opens a kdialog explaining why direct installation is not supported on an immutable image and pointing to Flatpak or distrobox as the alternatives.

For .rpm and .deb: search Flatpak first. If the app is not on Flathub, install via Distrobox using the matching distro’s package manager (Fedora distrobox for .rpm, Debian/Ubuntu distrobox for .deb).

For .exe and .msi: install Bottles or Wine from Flathub, or run the executable via Steam’s Proton if it is a game.

The handler is informational only. It does not attempt to install the file. To bypass and use a different handler, right-click the file and pick “Open With”.