main-desktop

Ubuntu 26.04 LTS on my desktop (Ryzen 7 9800X3D, RTX 5090, 49" 5120x1440), installed from a custom ISO that wipes the drive and sets the whole machine up without being watched. This replaces the Bazzite/BlueBuild image that used to live here — that version is still in the git history.

File	What it is
scripts/build-iso.sh	Builds the install ISO: stock Ubuntu desktop ISO + this repo + the autoinstall config
iso/user-data.in	The autoinstall config — which disk to wipe, the user, the driver and codec choices
scripts/setup.sh	Installs everything (drivers, Docker, Steam, Flatpaks, mounts). Runs itself on first boot; also runnable by hand on a stock Ubuntu install
scripts/firstboot.sh	The one-shot first-boot wrapper that calls setup.sh
flatpaks.txt	The app list

Copying files over and signing in to apps are deliberately not automated — I do those by hand.

Why leave Bazzite

The read-only base made ordinary things into projects. VS Code had to be layered with rpm-ostree, Node and .NET came from Homebrew, and Claude desktop ran inside an Ubuntu distrobox because it only ships for Ubuntu/Debian. On Ubuntu, each of those is an apt install.

1. Build the ISO

scripts/build-iso.sh

It asks for the login password to bake in, downloads the Ubuntu 26.04.1 desktop ISO if build/ doesn't have it (~6 GB, resumable, checksum-verified), and writes build/main-desktop-<date>.iso. The image surgery runs in a container, so the build machine needs nothing but podman — it works from Bazzite as-is.

The ISO holds your password hash, so treat the stick as private.

Write it to a USB stick — check the device name first, lsblk before you dd:

sudo dd if=build/main-desktop-<date>.iso of=/dev/sdX bs=4M status=progress oflag=direct conv=fsync

2. Boot it and pick the last GRUB entry

Install main-desktop UNATTENDED — ERASES the target disk

It is deliberately not the default entry: left alone, the stick boots into the ordinary Ubuntu installer, so an accidental boot can't wipe anything. The other entries are untouched.

What keeps this from eating the wrong disk

The autoinstall config matches one disk by serial — S73VNU0Y101555E, the 1 TB Samsung 990 PRO. The other NVMe in this machine (the 970 EVO Plus, "Data", serial S6P7NS0X656465Z, holding the second Steam library and the emulator files) never matches, and if no disk matches the installer stops instead of guessing. The same goes for any other machine you boot the stick on: it refuses rather than picking something.

Verified by installing from this ISO in a VM with two virtual NVMe drives carrying exactly those two serials: the 990 PRO one came out partitioned (1 GB ESP + root) with Ubuntu on it, and the Data one was byte-for-byte identical afterwards, marker file and all. The whole install ran without a keypress and rebooted on its own.

From there it runs on its own: partition, install Ubuntu desktop, install the NVIDIA driver and media codecs, then reboot.

3. First boot installs the apps

A one-shot service runs setup.sh the first time the new system boots. It needs the network, takes a while (roughly 12 GB of Flatpaks), and logs to /var/log/main-desktop-firstboot.log:

tail -f /var/log/main-desktop-firstboot.log

You can log in and use the machine while it works. It installs:

• Gaming: Steam (plus steam-devices for controllers), Lutris, GameMode, MangoHud, and ProtonUp-Qt for Proton-GE. The Xbox Bluetooth fix (disable_ertm) carries over from Bazzite.
• Containers: Docker CE from Docker's repo (not the snap), with --gpus all wired up through nvidia-container-toolkit. You're added to docker and kvm.
• Apps: the 27 Flatpaks in flatpaks.txt, picked from the 42 that were on Bazzite. The rest sit commented out at the bottom of that file. Ubuntu's Firefox snap is removed in favour of the Flatpak. A systemd timer updates Flatpaks daily.
• Dev: VS Code, Claude desktop (Anthropic's apt repo), Claude Code CLI, build-essential and cmake, and git credentials kept in the GNOME keyring. No Node or .NET on the host by choice — LudosData and landingPage build in Docker. To add them: sudo add-apt-repository ppa:jdxcode/mise && sudo apt install mise dotnet-sdk-10.0.
• Mounts: the Data drive at /mnt/data. The server-marvin share is skipped on an unattended run; run setup.sh again by hand if you want it, and it'll ask for the credentials.

The installer grants passwordless sudo for that one run; firstboot.sh takes it away again on its way out, whether setup.sh succeeded or not.

4. Then, by hand

• Log out and back in — the docker and kvm groups need a fresh session.
• Steam: sign in, then Settings → Storage → Add drive → /mnt/data/SteamLibrary. Those games need no redownload.
• Display: Settings → Displays. The monitor does 5120x1440 @ 240 Hz; Bazzite was running it at 120. Turn on variable refresh rate while you're there.
• PIA VPN: the official Linux app works on Ubuntu (it couldn't on Bazzite's read-only /usr). Download the installer from PIA and run it.
• Gitea: the first git push asks for your username and password once, then the GNOME keyring remembers it. KDE Wallet was doing that here.

Moving files across by hand

• Flatpak app data lives in ~/.var/app/<app-id>. Copying one app's folder across brings that app's logins, profile and settings with it — Firefox and Thunderbird profiles included.
• Steam saves are in ~/.local/share/Steam/userdata (Proton prefixes in steamapps/compatdata). Game files themselves redownload.
• FFXIV is ~/.xlcore, ~124 GB. Worth copying rather than re-fetching from Square's servers.
• ComfyUI: copy the folder but not its venv — rebuild that with python3 -m venv venv && venv/bin/pip install -r requirements.txt.
• Don't copy Fedora's .bashrc/.bash_profile, ~/.local/bin (pip shims built against Fedora's Python), ~/.config/dconf (KDE's settings database, which would overwrite GNOME's), or the KDE-generated ~/.config/gtk-3.0 and gtk-4.0 themes.

Check it worked

nvidia-smi                         # RTX 5090, driver 595.x
modinfo -F license nvidia          # "Dual MIT/GPL" = open modules
docker run --rm --gpus all nvidia/cuda:12.8.0-base-ubuntu24.04 nvidia-smi
flatpak list --app | wc -l         # 27
findmnt /mnt/data
claude --version && code --version
systemctl status main-desktop-firstboot   # should be a completed one-shot, now disabled

Podman's --device nvidia.com/gpu=all needs a CDI spec. The toolkit normally generates one at boot; if Podman says the device is unknown, run sudo nvidia-ctk cdi generate --output=/etc/cdi/nvidia.yaml.

Without the ISO

Install Ubuntu 26.04 by hand (user ckoch — the first user gets UID 1000, which matches the file ownership on the Data drive), then:

sudo apt install -y git
git clone https://git.lazypugs.com/ckoch/main-desktop.git ~/Documents/git/main-desktop
cd ~/Documents/git/main-desktop && scripts/setup.sh      # safe to re-run

Reboot when it finishes, then sudo flatpak update once — Flatpak can only match its NVIDIA GL runtime to a driver that's already loaded, so apps render in software until that happens (the daily timer catches it about 10 minutes after boot anyway). The ISO route avoids this, because the driver is already installed before the apps are.

Coming from Bazzite: what moved

Was	Now
rpm-ostree layering / ujust	apt
Homebrew node@24, dotnet	Nothing on the host — those projects build in Docker
Claude desktop in a distrobox	Native claude-desktop package
Git password from KDE Wallet	GNOME keyring, via git's libsecret helper
/var/home/ckoch	/home/ckoch
/run/media/ckoch/Data	/mnt/data
/var/mnt/server-marvin-personal	/mnt/server-marvin-personal
Image updates + rollback	Software Updater / sudo apt update && sudo apt upgrade; Flatpaks auto-update daily. No rollback by default; sudo apt install timeshift if you miss it

Maintenance

• Add or remove an app: edit flatpaks.txt, then re-run scripts/setup.sh on the machine (or rebuild the ISO for the next install). Removing a line doesn't uninstall anything; flatpak uninstall <id> once by hand.
• New Ubuntu point release: bump UBUNTU_POINT in scripts/build-iso.sh and rebuild.
• Next LTS (28.04): Ubuntu offers the upgrade in Software Updater once 28.04.1 is out. The upgrader disables third-party repos (Docker, NVIDIA toolkit, and so on) — turn them back on in Software & Updates → Other Software afterwards.
• The ISO's own "Check disc for defects" option will report mismatches, since the added files aren't in the stock md5sum.txt. That's expected and doesn't affect installing.