(automake-1.16.info)A Library

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8.2 Building a library
======================

Building a library is much like building a program.  In this case, the
name of the primary is ‘LIBRARIES’.  Libraries can be installed in
‘libdir’ or ‘pkglibdir’.

   Note: A Shared Library, for information on how to build shared
libraries using libtool and the ‘LTLIBRARIES’ primary.

   Each ‘_LIBRARIES’ variable is a list of the libraries to be built.
For instance, to create a library named ‘libcpio.a’, but not install it,
you would write:

     noinst_LIBRARIES = libcpio.a
     libcpio_a_SOURCES = ...

   The sources that go into a library are determined exactly as they are
for programs, via the ‘_SOURCES’ variables.  Note that the library name
is canonicalized (Note: Canonicalization), so the ‘_SOURCES’ variable
corresponding to ‘libcpio.a’ is ‘libcpio_a_SOURCES’, not
‘libcpio.a_SOURCES’.

   Extra objects can be added to a library using the ‘LIBRARY_LIBADD’
variable.  This should be used for objects determined by ‘configure’.
Again from ‘cpio’:

     libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA)

   In addition, sources for extra objects that will not exist until
configure-time must be added to the ‘BUILT_SOURCES’ variable (Note:
Sources).

   Building a static library is done by compiling all object files, then
by invoking ‘$(AR) $(ARFLAGS)’ followed by the name of the library and
the list of objects, and finally by calling ‘$(RANLIB)’ on that library.
You should call ‘AC_PROG_RANLIB’ from your ‘configure.ac’ to define
‘RANLIB’ (Automake will complain otherwise).  You should also call
‘AM_PROG_AR’ to define ‘AR’, in order to support unusual archivers such
as Microsoft lib.  ‘ARFLAGS’ will default to ‘cru’; you can override
this variable by setting it in your ‘Makefile.am’ or by ‘AC_SUBST’ing it
from your ‘configure.ac’.  You can override the ‘AR’ variable by
defining a per-library ‘maude_AR’ variable (Note: Program and Library
Variables).

   Be careful when selecting library components conditionally.  Because
building an empty library is not portable, you should ensure that any
library always contains at least one object.

   To use a static library when building a program, add it to ‘LDADD’
for this program.  In the following example, the program ‘cpio’ is
statically linked with the library ‘libcpio.a’.

     noinst_LIBRARIES = libcpio.a
     libcpio_a_SOURCES = ...

     bin_PROGRAMS = cpio
     cpio_SOURCES = cpio.c ...
     cpio_LDADD = libcpio.a