The Documentation Build ProcessThis chapter's main purpose is to clearly explain
how the documentation build process is
organized, and how to affect modifications
to this process.After you have finished reading this chapter you
should:Know what you need to build the FDP documentation, in
addition to those mentioned in the
SGML tools chapter.Be able to read and understand the
make instructions that are present
in each document's Makefiles, as well as
an overview of the doc.project.mk
includes.Be able to customize the build process by using
make variables and
make targets.The FreeBSD Documentation Build ToolsetHere are your tools. Use them every way you can.The primary build tool you will need is
make, but specifically
Berkeley Make.Package building is handled by FreeBSD's
pkg_create. If you are not using
FreeBSD, you will either have to live without packages, or
compile the source yourself.gzip is needed to create
compressed versions of the document.
bzip2 compression and
zip archives are also supported.
tar is supported, but package
building demands it.install is the default method
to install the documentation. There are alternatives,
however.It is unlikely you will have any trouble finding these
last two, they are mentioned for completeness only.Understanding Makefiles in the
Documentation TreeThere are three main types of Makefiles
in the FreeBSD Documentation Project tree.Subdirectory
Makefiles simply pass
commands to those directories below them.Documentation
Makefiles describe the
document(s) that should be produced from this
directory.Make
includes are the glue that perform the document
production, and are usually of the form
doc.xxx.mk.Subdirectory MakefilesThese Makefiles usually take the form
of:SUBDIR =articles
SUBDIR+=books
COMPAT_SYMLINK = en
DOC_PREFIX?= ${.CURDIR}/..
.include "${DOC_PREFIX}/share/mk/doc.project.mk"In quick summary, the first four non-empty lines define
the make variables,
SUBDIR, COMPAT_SYMLINK,
and DOC_PREFIX.The first SUBDIR statement, as well as
the COMPAT_SYMLINK statement, shows how to
assign a value to a variable, overriding any previous
value.The second SUBDIR statement shows how a
value is appended to the current value of a variable. The
SUBDIR variable is now articles
books.The DOC_PREFIX assignment shows how a
value is assigned to the variable, but only if it is not
already defined. This is useful if
DOC_PREFIX is not where this
Makefile thinks it is - the user can
override this and provide the correct value.Now what does it all mean? SUBDIR
mentions which subdirectories below this one the build process
should pass any work on to.COMPAT_SYMLINK is specific to
compatibility symlinks (amazingly enough) for languages to
their official encoding (doc/en would
point to en_US.ISO-8859-1).DOC_PREFIX is the path to the root of
the FreeBSD Document Project tree. This is not always that
easy to find, and is also easily overridden, to allow for
flexibility. .CURDIR is a
make builtin variable with the path
to the current directory.The final line includes the FreeBSD Documentation
Project's project-wide make system
file doc.project.mk which is the glue
which converts these variables into build instructions.Documentation MakefilesThese Makefiles set a bunch of
make variables that describe how to
build the documentation contained in that directory.Here is an example:MAINTAINER=nik@FreeBSD.org
DOC?= book
FORMATS?= html-split html
INSTALL_COMPRESSED?= gz
INSTALL_ONLY_COMPRESSED?=
# SGML content
SRCS= book.sgml
DOC_PREFIX?= ${.CURDIR}/../../..
.include "$(DOC_PREFIX)/share/mk/docproj.docbook.mk"The MAINTAINER variable is a very
important one. This variable provides the ability to claim
ownership over a document in the FreeBSD Documentation
Project, whereby you gain the responsibility for maintaining
it.DOC is the name (sans the
.sgml extension) of the main document
created by this directory. SRCS lists all
the individual files that make up the document. This should
also include important files in which a change should result
in a rebuild.FORMATS indicates the default formats
that should be built for this document.
INSTALL_COMPRESSED is the default list of
compression techniques that should be used in the document
build. INSTALL_ONLY_COMPRESS, empty by
default, should be non-empty if only compressed documents are
desired in the build.We covered optional variable assignments in the
previous section.The DOC_PREFIX and include statements
should be familiar already.FreeBSD Documentation Project
Make IncludesThis is best explained by inspection of the code. Here are
the system include files:doc.project.mk is the main project
include file, which includes all the following include
files, as necessary.doc.subdir.mk handles traversing of
the document tree during the build and install
processes.doc.install.mk provides variables
that affect ownership and installation of documents.doc.docbook.mk is included if
DOCFORMAT is docbook
and DOC is set.doc.project.mkBy inspection:DOCFORMAT?= docbook
MAINTAINER?= doc@FreeBSD.org
PREFIX?= /usr/local
PRI_LANG?= en_US.ISO8859-1
.if defined(DOC)
.if ${DOCFORMAT} == "docbook"
.include "doc.docbook.mk"
.endif
.endif
.include "doc.subdir.mk"
.include "doc.install.mk"VariablesDOCFORMAT and
MAINTAINER are assigned default values,
if these are not set by the document make file.PREFIX is the prefix under which the
documentation building tools
are installed. For normal package and port installation,
this is /usr/local.PRI_LANG should be set to whatever
language and encoding is natural amongst users these
documents are being built for. US English is the
default.PRI_LANG in no way affects what
documents can, or even will, be built. Its main use is
creating links to commonly referenced documents into the
FreeBSD documentation install root.ConditionalsThe .if defined(DOC) line is an
example of a make conditional
which, like in other programs, defines behavior if some
condition is true or if it is false.
defined is a function which returns
whether the variable given is defined or not..if ${DOCFORMAT} == "docbook", next,
tests whether the DOCFORMAT variable is
"docbook", and in this case, includes
doc.docbook.mk.The two .endifs close the two above
conditionals, marking the end of their application.doc.subdir.mkThis is too long to explain by inspection, you should be
able to work it out with the knowledge gained from the
previous chapters, and a little help given here.VariablesSUBDIR is a list of
subdirectories that the build process should go further
down into.ROOT_SYMLINKS is the name of
directories that should be linked to the document
install root from their actual locations, if the current
language is the primary language (specified by
PRI_LANG).COMPAT_SYMLINK is described in
the
Subdirectory Makefile
section.Targets and MacrosDependencies are described by
target:
dependency1 dependency2
... tuples, where to build
target, you need to build the given
dependencies first.After that descriptive tuple, instructions on how to
build the target may be given, if the conversion process
between the target and its dependencies are not previously
defined, or if this particular conversion is not the same as
the default conversion method.A special dependency .USE defines
the equivalent of a macro._SUBDIRUSE: .USE
.for entry in ${SUBDIR}
@${ECHO} "===> ${DIRPRFX}${entry}"
@(cd ${.CURDIR}/${entry} && \
${MAKE} ${.TARGET:S/realpackage/package/:S/realinstall/install/} DIRPRFX=${DIRPRFX}${entry}/ )
.endforIn the above, _SUBDIRUSE is now
a macro which will execute the given commands when it is
listed as a dependency.What sets this macro apart from other targets?
Basically, it is executed after the
instructions given in the build procedure it is listed as a
dependency to, and it does not adjust
.TARGET, which is the variable which
contains the name of the target currently being
built.clean: _SUBDIRUSE
rm -f ${CLEANFILES}In the above, clean will use
the _SUBDIRUSE macro after it has
executed the instruction
rm -f ${CLEANFILES}. In effect, this
causes clean to go further and
further down the directory tree, deleting built files as it
goes down, not on the way back
up.Provided Targetsinstall and
package both go down the
directory tree calling the real versions of themselves
in the subdirectories
(realinstall and
realpackage
respectively).clean removes files
created by the build process (and goes down the
directory tree too).
cleandir does the same, and
also removes the object directory, if any.More on Conditionalsexists is another condition
function which returns true if the given file
exists.empty returns true if the given
variable is empty.target returns true if the given
target does not already exist.Looping Constructs in make
(.for).for provides a way to repeat a set
of instructions for each space-separated element in a
variable. It does this by assigning a variable to contain
the current element in the list being examined._SUBDIRUSE: .USE
.for entry in ${SUBDIR}
@${ECHO} "===> ${DIRPRFX}${entry}"
@(cd ${.CURDIR}/${entry} && \
${MAKE} ${.TARGET:S/realpackage/package/:S/realinstall/install/} DIRPRFX=${DIRPRFX}${entry}/ )
.endforIn the above, if SUBDIR is empty, no
action is taken; if it has one or more elements, the
instructions between .for and
.endfor would repeat for every element,
with entry being replaced with the value
of the current element.