source: README.PACKAGE_MANAGEMENT

TITLE : Package management in jhalfs
BY    : Pierre Labastie (work in progress)

1. INTRODUCTION:

      There are several hints discussing package management for LFS, but
  nothing under jhalfs. There used to be a patch for PACO that I cannot
  find now. So there was a need for such a tool, and an infrastructure,
  which allows using a package manager inside jhalfs, has been developped.
  I hope it is flexible enough to support several package managers, at least
  among those who use DESTDIR install and/or LD_PRELOAD during install.
  It has been tested with dpkg from Debian, pacman from Arch Linux,
  and porg. Sample configuration files are given for those three packages.
  I am sorry to say I have (almost) no experience with rpm, so I cannot
  tell whether it would fit.

2. OVERVIEW OF THE SYSTEM:

      For now, package management is only available for LFS. The `porg style'
  (see below) package management has been ported to BLFS, but not the distro
  style one (the book layout makes it rather difficult).

      This tool comes in two flavours:
  - for distros package managers (e.g dpkg or pacman), it basically performs
    a "DESTDIR install" for all pages in chapter 8, 9 and 10 of the book. The
    name of the DESTDIR directory is the same as the one of the executed
    script. The path to this directory is available to the scriplets through
    the PKG_DEST variable. The details of the DESTDIR part are given below.
    After the package is installed in $PKG_DEST, a function "packInstall" is
    called, which is supposed to create a binary package (e.g. make a .deb
    file), store it to a repository and install it to the system.
  - for porg style package manager, the install instructions are wrapped
    between pairs of single quotes ('). This allows passing those instructions
    to a function ("wrapInstall"), which may itself call porg or another
    (e.g. fakeroot, not tested) instruction wrapper. Note that if the
    instructions contain single quote charaters, they are changed to '\'',
    which pass them literally. At the end of the installation, a function
    "packInstall" is called, with a slighly different aim compared to the
    DESTDIR one: it is used to make a tarball of the installed files (e.g.
    using "porgball") and store them into some repository. But there is no
    need to install them to the system, since this has already been done.

      Note that with carefully crafted "packInstall" and "wrapInstall"
  functions, a combination of the two methods could be used, for example for
  DESTDIR installs using fakeroot. This is work in progress and not fully
  implemented yet (well... Closer to a wish list actually).

3. DETAILS:

      The XSL stylesheet used for generating the scriptlets, automatically
  adds DESTDIR install instructions when "package management" is selected.
  Also all the paths beginning with " /" or ">/" (absolute paths) are prepended
  with $PKG_DEST. This has the default that you might want to move
  files to non existent directories. There is no simple way to automatically
  create those directories, because you have sometimes to use the full path
  (instructions of the form `cp file dir') and sometimes only the dirname
  (instructions of the form `cp file1 file2'). So the XSL stylesheet
  creates a reasonable subset of the FHS hierarchy into the destination
  directory. Empty directories are then removed before packing the
  binary package.

      In order to use the package manager, it has to be installed at the end of
  chapter 7 (temporary installation) and chapter 8 (final install).
  Furthermore, the administrative files and directories have to be created
  during the `Creating Directories' and `Creating Essential Files' stages.
  For all this, the user has to supply a file in docbook XML format, with
  the necessary instructions and enough information to download the tarball.
  This file should reside in the `pkgmngt' directory and be named
  `packageManager.xml'. A template named `packageManager.xml.template' is
  provided in the `pkgmngt' subdirectory. There are also three XML files for
  dpkg, pacman, and porg, respectively `packageManager.xml.dpkg',
  `packageManager.xml.pacman',  and `packageManager.xml.porg', that you can
  copy to `packageManager.xml' and modify to suit your needs.
  They are not updated often, so the versions used can be rather old.

      The last thing to do is to tell how to use the package manager. The user
  has to provide two functions, "wrapInstall" and "packInstall", as described
  above. Please note that nothing has been done to manage configuration files,
  which are ususally treated specially by package managers: depending on
  the book layout, it is sometimes possible to create those files afterwards,
  and sometimes not, which means that you have to check them after each
  upgrade. Both functions should be defined in a file named `packInstall.sh',
  residing in the `pkgmngt' directory. A template is provided (actually a copy
  of the file for dpkg), as well as three example scripts for dpkg, pacman,
  and porg. Pacman Note: due to the way pacman checks the available space on
  disk, the root directory in chroot must be a mount point, otherwise the
  installation of packages fails.