This chapter's main purpose is to clearly explain how the documentation build process is organised, 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. Here 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 not be able to find these last two, they are mentioned for completeness. There 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. These directories 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. These 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. This 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. By 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" DOCFORMAT 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. The .if defined(DOC) line is an example of a make conditional which, like in other programs, defines behaviour 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. This 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. SUBDIR 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. Dependencies 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}/ ) .endfor In 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. install 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. exists 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. .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}/ ) .endfor In 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.