dpkg-fsys-usrunmess - undoes the merged-/usr-via-aliased-dirs
mess
dpkg-fsys-usrunmess [option...]
dpkg-fsys-usrunmess is a tool to fix up filesystems that
have been installed anew with recent installers with unfortunate defaults or
migrated to the broken merged /usr via aliased directories layout, which is
not supported by dpkg. See the dpkg FAQ.
Note: In Debian its tech-ctte has decreed that on the
release after bookworm the non-usrmerged layout is not going to be
supported, and thus some of its maintainers might not fix issues or
intentionally remove non-usrmerged support, so you will need decide and pick
your poison.
The program will perform the following overall actions:
- Check whether the system needs to be switched, otherwise do nothing,
- Check for dpkg database consistency and otherwise abort.
- Generate and install a regression prevention package, if requested on the
command-line or otherwise on the prompt.
- Get the list of files and alternatives that need to be restored.
- Look for untracked kernel modules files that need to be moved too.
- Create a shadow hierarchy under /.usrunmess, by creating the
directories symlinks or hardlinking or copying the files as needed.
- Prompt for confirmation before proceeding, if requested on the
command-line.
- Lock the dpkg database.
- Mark all packages as half-configured to force running maintainer scripts
that might need to recreate files.
- Replace the aliased directories with the shadow ones, by creating a backup
of the old symlinked directories and renaming the shadow ones over.
- Relabel MAC information for directories and symlinks if necessary.
- Remove backup symlinks.
- Remove old moved objects, but defer directory removal.
- Remove old deferred directories that are not referenced by
dpkg-query.
- Remove shadow root directory.
- Register a policy-rc.d to disallow service actions, which means
that services might need to be restarted afterwards, ideally via a
reboot.
- Reconfigure all packages.
- Unregister the policy-rc.d and restore the alternatives state.
Note: When running the program from some shells such as
bash(1) or zsh(1), after executing it, you might need to
request the shell to forget all remembered executable locations with for
example "hash -r".
Note: Some directories might linger after the migration in
case they contain untracked files. A list is printed once the script has
finished for further investigation.
Warning: Note that this operation has the potential to
render the system unusable or broken in case of a sudden crash or reboot,
unexpected state of the system, or possible bugs in the script. Be prepared
with recovery media and consider doing backups beforehand.
- -p, --prompt
- Prompt at the time of no return, so that the debug output or the shadow
hierarchy can be evaluated before proceeding.
- --prevention
- --no-prevention
- Enables or disables generating and installing a regression prevention
package into the system. If no option has been specified, the action to
take will be prompted.
The generated package contains the Protected field set
to yes to protect against accidental removal of the package.
- -n, --no-act
- --dry-run
- This option enables the dry-run mode, where no destructive action takes
place, only the preparatory part.
- -?, --help
- Show the usage message and exit.
- --version
- Show the version and exit.
<https://wiki.debian.org/Teams/Dpkg/FAQ#broken-usrmerge>.