Levels 74–77: Universal Packages

Level 74: Installing with Snap

apt, dnf, and pacman install packages built for one distro’s exact library versions. Every snap bundles its own dependencies and runs sandboxed, so it installs identically anywhere snapd runs.

Command	What it does
`snap install spotify`	Install a snap
`snap list`	List installed snaps
`snap info spotify`	Details before installing
`snap remove spotify`	Uninstall
`snap install code --classic`	Install with full system access instead of the normal sandbox

Level 75: Snap Channels & Updates

Command	What it does
`snap refresh`	Check for and install updates to everything installed
`snap install mytool --channel=edge`	Install tracking a specific release channel
`snap list --all mytool`	See every kept revision, not just the active one
`snap revert mytool`	Roll back to the previous working revision
`snap disable mytool`	Disable without uninstalling

Level 76: Installing with Flatpak

Flathub is the community app store almost every flatpak setup points at by default.

Command	What it does
`flatpak install flathub org.gimp.GIMP`	Install an app from a remote
`flatpak run org.gimp.GIMP`	Launch by app ID
`flatpak list`	List installed flatpaks
`flatpak uninstall org.gimp.GIMP`	Remove an app
`flatpak uninstall --unused`	Clean up orphaned shared runtimes

Level 77: Flatpak Remotes

Command	What it does
`flatpak remote-add --if-not-exists flathub <url>`	Wire up the flathub remote
`flatpak remotes`	List configured remotes
`flatpak update`	Update everything installed
`flatpak search video editor`	Search flathub by keyword
namespaces	The Linux kernel isolation feature flatpak sandboxing is built on (via bubblewrap), versus snap’s AppArmor-based confinement

Finish this tier and move on to Terminal Multiplexing: tmux, and why an SSH session dropping doesn’t have to mean your work dies with it.