What d77void Immutable is
d77void Immutable is a variant of d77void where the operating system is a single read-only image. You do not install or update packages one by one: a new version of the whole system arrives as a new image, and the previous one stays on the disk so you can go back to it.
“Immutable” means the same here as on Fedora Silverblue: the system files do not change while it runs, but your settings, your data and your applications are kept.
- Base: Void Linux (glibc, x86_64) with runit. There is no systemd.
- Desktop: KDE Plasma.
- Applications: Flatpak (Discover and Flathub) for graphical programs, Distrobox for command-line and development tools. See Where to install applications.
- Updates: automatic, whole-image, signed, with automatic fallback. See A/B slots and updates.
How it differs from a regular Void installation
| Regular Void | d77void Immutable | |
|---|---|---|
| The system | files installed by packages, changed in place | one read-only image per version |
| Installing software | xbps-install | Flatpak, Distrobox, AppImage |
| Updating | xbps-install -Su, package by package | a whole new image, in the background |
| If an update breaks something | fix it by hand | the previous version is still there |
| Package manager on the installed system | yes | no: xbps-install fails on purpose |
xbps-install is present in the image, but it cannot change anything: the
system’s files and the package database are read-only. That is expected, not
an error. Use the methods in
Where to install applications instead.
What is read-only and what is kept
At boot, the system puts together its root directory from the image of the version being started and from the persistent data on the disk:
| Path | Behaviour |
|---|---|
/usr | Read-only. Comes from the image; a new version replaces it. |
/etc | Kept. Your changes are stored on the disk, on top of the image’s files. |
/var | Kept. System Flatpak applications, logs, network settings and other state live here. |
/home | Kept. Your files. |
/root | Kept. The root user’s home. |
Everything else under / (for example /opt) | Writable, but reset on every boot. Anything written there is gone after a restart. |
The kept data is the same whichever version you start: going back to the previous version keeps your files and settings.
Changes to /etc are kept, but a file you change stops following new
versions of the image; d77-etc-diff shows and undoes those changes. See
What is kept for the details.
Things that work differently
- Do not copy programs into
/usror/opt./usris read-only, and/optis emptied on every boot. Put them in your home, or use one of the methods in Where to install applications. - Changes to the system itself come with a new version, not by editing it on the running machine.
- Restarting is how an update takes effect. The new version is downloaded in the background and starts on the next boot.