Automake variables generally follow a uniform naming scheme that
makes it easy to decide how programs (and other derived objects) are
built, and how they are installed. This scheme also supports
configure time determination of what should be built.
At make time, certain variables are used to determine which
objects are to be built. The variable names are made of several pieces
that are concatenated together.
The piece that tells automake what is being built is commonly called
the primary. For instance, the primary PROGRAMS holds a
list of programs that are to be compiled and linked.
A different set of names is used to decide where the built objects
should be installed. These names are prefixes to the primary, and they
indicate which standard directory should be used as the installation
directory. The standard directory names are given in the GNU standards
(see Directory Variables in The GNU Coding Standards).
Automake extends this list with pkgdatadir, pkgincludedir,
pkglibdir, and pkglibexecdir; these are the same as the
non-‘pkg’ versions, but with ‘$(PACKAGE)’ appended. For instance,
pkglibdir is defined as ‘$(libdir)/$(PACKAGE)’.
For each primary, there is one additional variable named by prepending
‘EXTRA_’ to the primary name. This variable is used to list
objects that may or may not be built, depending on what
configure decides. This variable is required because Automake
must statically know the entire list of objects that may be built in
order to generate a Makefile.in that will work in all cases.
For instance, cpio decides at configure time which programs
should be built. Some of the programs are installed in bindir,
and some are installed in sbindir:
EXTRA_PROGRAMS = mt rmt bin_PROGRAMS = cpio pax sbin_PROGRAMS = $(MORE_PROGRAMS)
Defining a primary without a prefix as a variable, e.g., ‘PROGRAMS’, is an error.
Note that the common ‘dir’ suffix is left off when constructing the variable names; thus one writes ‘bin_PROGRAMS’ and not ‘bindir_PROGRAMS’.
Not every sort of object can be installed in every directory. Automake will flag those attempts it finds in error (but see below how to override the check if you need to). Automake will also diagnose obvious misspellings in directory names.
Sometimes the standard directories—even as augmented by Automake—are not enough. In particular it is sometimes useful, for clarity, to install objects in a subdirectory of some predefined directory. To this end, Automake allows you to extend the list of possible installation directories. A given prefix (e.g., ‘zar’) is valid if a variable of the same name with ‘dir’ appended is defined (e.g., ‘zardir’).
For instance, the following snippet will install file.xml into ‘$(datadir)/xml’.
xmldir = $(datadir)/xml xml_DATA = file.xml
This feature can also be used to override the sanity checks Automake performs to diagnose suspicious directory/primary couples (in the unlikely case that you need to omit these checks). For example, Automake would error out on this input:
# Forbidden directory combinations, automake will error out on this. pkglib_PROGRAMS = foo doc_LIBRARIES = libquux.a
but it will succeed with this:
# Work around forbidden directory combinations. Do not use this # without a very good reason! my_execbindir = $(pkglibdir) my_doclibdir = $(docdir) my_execbin_PROGRAMS = foo my_doclib_LIBRARIES = libquux.a
The ‘exec’ substring of the ‘my_execbindir’ variable lets the files be installed at the right time (see The Two Parts of Install).
The special prefix ‘noinst_’ indicates that the objects in question should be built but not installed at all. This is usually used for objects required to build the rest of your package, for instance static libraries (see Building a library), or helper scripts.
The special prefix ‘check_’ indicates that the objects in question should not be built until the ‘make check’ command is run. Those objects are not installed either.
The current primary names are ‘PROGRAMS’, ‘LIBRARIES’, ‘LTLIBRARIES’, ‘LISP’, ‘PYTHON’, ‘JAVA’, ‘SCRIPTS’, ‘DATA’, ‘HEADERS’, ‘MANS’, and ‘TEXINFOS’.
Some primaries also allow additional prefixes that control other
aspects of automake’s behavior. The currently defined prefixes
are ‘dist_’, ‘nodist_’, ‘nobase_’, and ‘notrans_’.
These prefixes are explained later (see Program and Library Variables)
(see Man Pages).