dpkg-fsys-usrunmess(8)    (2021-04-13)     dpkg-fsys-usrunmess(8)

     NAME
          dpkg-fsys-usrunmess - undoes the
          merged-/usr-via-aliased-dirs mess

     SYNOPSIS
          dpkg-fsys-usrunmess [option...]

     DESCRIPTION
          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.

          The program will perform the following overall actions:

          +o   Check whether the system needs to be switched, otherwise
              do nothing,

          +o   Check for dpkg database consistency and otherwise abort.

          +o   Get the list of files and alternatives that need to be
              restored.

          +o   Create a shadow hierarchy under /.usrunmess, by creating
              the directories symlinks or hardlinking or copying the
              files as needed.

          +o   Prompt for confirmation before proceeding, if requested
              on the command-line.

          +o   Lock the dpkg database.

          +o   Mark all packages as half-configured to force running
              maintainer scripts that might need to recreate files.

          +o   Replace the aliased directories with the shadow ones, by
              creating a backup of the old symlinked directories and
              renaming the shadow ones over.

          +o   Relabel MAC information for directories and symlinks if
              necessary.

          +o   Reconfigure all packages.

          +o   Remove backup symlinks.

          +o   Remove old moved objects, but defer directory removal.

          +o   Remove old deferred directories that are not referenced

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     dpkg-fsys-usrunmess(8)    (2021-04-13)     dpkg-fsys-usrunmess(8)

              by dpkg-query.

          +o   Remove shadow root directory.

          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".

          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.

     OPTIONS
          -p, --prompt
              Prompt at the time of no return, so that the debug
              output or the shadow hierarchy can be evaluated before
              proceeding.

          -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.

     ENVIRONMENT
          DPKG_USRUNMESS_NOACT
              This setting defines whether to enable dry-run mode.

     SEE ALSO
          <https://wiki.debian.org/Teams/Dpkg/FAQ#Q:_Does_dpkg_support_merged-.2Fusr-via-aliased-dirs.3F>.

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