This file documents the GNU Automake package. Automake is a program which creates GNU standards-compliant Makefiles from template files. This edition documents version 1.7.8.
Automake is a tool for automatically generating Makefile.ins from
files called Makefile.am. Each Makefile.am is basically a
series of make variable definitions1, with
rules being thrown in occasionally. The generated Makefile.ins
are compliant with the GNU Makefile standards.
The GNU Makefile Standards Document (see Makefile Conventions) is long, complicated, and subject to change. The goal of Automake is to remove the burden of Makefile maintenance from the back of the individual GNU maintainer (and put it on the back of the Automake maintainer).
The typical Automake input file is simply a series of variable definitions.
Each such file is processed to create a Makefile.in. There
should generally be one Makefile.am per directory of a project.
Automake does constrain a project in certain ways; for instance it
assumes that the project uses Autoconf (see Introduction), and enforces certain restrictions on
the configure.in contents2.
Automake requires perl in order to generate the
Makefile.ins. However, the distributions created by Automake are
fully GNU standards-compliant, and do not require perl in order
to be built.
Mail suggestions and bug reports for Automake to bug-automake@gnu.org.
The following sections cover a few basic ideas that will help you understand how Automake works.
Automake works by reading a Makefile.am and generating a
Makefile.in. Certain variables and targets defined in the
Makefile.am instruct Automake to generate more specialized code;
for instance, a bin_PROGRAMS variable definition will cause targets
for compiling and linking programs to be generated.
The variable definitions and targets in the Makefile.am are copied
verbatim into the generated file. This allows you to add arbitrary code
into the generated Makefile.in. For instance the Automake
distribution includes a non-standard cvs-dist target, which the
Automake maintainer uses to make distributions from his source control
system.
Note that most GNU make extensions are not recognized by Automake. Using
such extensions in a Makefile.am will lead to errors or confusing
behavior.
A special exception is that the GNU make append operator, +=, is
supported. This operator appends its right hand argument to the variable
specified on the left. Automake will translate the operator into
an ordinary = operator; += will thus work with any make program.
Automake tries to keep comments grouped with any adjoining targets or variable definitions.
A target defined in Makefile.am generally overrides any such
target of a similar name that would be automatically generated by
automake. Although this is a supported feature, it is generally
best to avoid making use of it, as sometimes the generated rules are
very particular.
Similarly, a variable defined in Makefile.am or AC_SUBST'ed
from configure.in will override any definition of the variable that
automake would ordinarily create. This feature is more often
useful than the ability to override a target definition. Be warned that
many of the variables generated by automake are considered to be for
internal use only, and their names might change in future releases.
When examining a variable definition, Automake will recursively examine
variables referenced in the definition. For example, if Automake is
looking at the content of foo_SOURCES in this snippet
xs = a.c b.c
foo_SOURCES = c.c $(xs)
it would use the files a.c, b.c, and c.c as the
contents of foo_SOURCES.
Automake also allows a form of comment which is not copied into
the output; all lines beginning with ## (leading spaces allowed)
are completely ignored by Automake.
It is customary to make the first line of Makefile.am read:
## Process this file with automake to produce Makefile.in
While Automake is intended to be used by maintainers of GNU packages, it does make some effort to accommodate those who wish to use it, but do not want to use all the GNU conventions.
To this end, Automake supports three levels of strictness--the strictness indicating how stringently Automake should check standards conformance.
The valid strictness levels are:
foreign
NEWS file, it will not be required in
this mode. The name comes from the fact that Automake is intended to be
used for GNU programs; these relaxed rules are not the standard mode of
operation.
gnu
gnits
For more information on the precise implications of the strictness level, see Gnits.
Automake also has a special "cygnus" mode which is similar to strictness but handled differently. This mode is useful for packages which are put into a "Cygnus" style tree (e.g., the GCC tree). For more information on this mode, see Cygnus.
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
which are concatenated together.
The piece which tells automake what is being built is commonly called
the primary. For instance, the primary PROGRAMS holds a
list of programs which 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 which
indicate which standard directory should be used as the installation
directory. The standard directory names are given in the GNU standards
(see Directory Variables).
Automake extends this list with pkglibdir, pkgincludedir,
and pkgdatadir; 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 which 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 are
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. 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, until HTML support is part of Automake, you could use this to install raw HTML documentation:
htmldir = $(prefix)/html
html_DATA = automake.html
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 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,
LISP, PYTHON, JAVA, SCRIPTS, DATA,
HEADERS, MANS, and TEXINFOS.
Some primaries also allow additional prefixes which control other
aspects of automake's behavior. The currently defined prefixes
are dist_, nodist_, and nobase_. These prefixes
are explained later (see Program and Library Variables).
Sometimes a Makefile variable name is derived from some text the
maintainer supplies. For instance, a program name listed in
_PROGRAMS is rewritten into the name of a _SOURCES
variable. In cases like this, Automake canonicalizes the text, so that
program names and the like do not have to follow Makefile variable naming
rules. All characters in the name except for letters, numbers, the
strudel (@), and the underscore are turned into underscores when making
variable references.
For example, if your program is named sniff-glue, the derived
variable name would be sniff_glue_SOURCES, not
sniff-glue_SOURCES. Similarly the sources for a library named
libmumble++.a should be listed in the
libmumble___a_SOURCES variable.
The strudel is an addition, to make the use of Autoconf substitutions in variable names less obfuscating.
Some Makefile variables are reserved by the GNU Coding Standards
for the use of the "user" - the person building the package. For
instance, CFLAGS is one such variable.
Sometimes package developers are tempted to set user variables such as
CFLAGS because it appears to make their job easier - they don't
have to introduce a second variable into every target.
However, the package itself should never set a user variable, particularly not to include switches which are required for proper compilation of the package. Since these variables are documented as being for the package builder, that person rightfully expects to be able to override any of these variables at build time.
To get around this problem, automake introduces an automake-specific
shadow variable for each user flag variable. (Shadow variables are not
introduced for variables like CC, where they would make no
sense.) The shadow variable is named by prepending AM_ to the
user variable's name. For instance, the shadow variable for
YFLAGS is AM_YFLAGS.
Automake sometimes requires helper programs so that the generated
Makefile can do its work properly. There are a fairly large
number of them, and we list them here.
ansi2knr.c
ansi2knr.1
compile
-c and
-o at the same time. It is only used when absolutely required.
Such compilers are rare.
config.guess
config.sub
ftp://ftp.gnu.org/gnu/config/> before making a release.
depcomp
elisp-comp
install-sh
install program which works on
platforms where install is unavailable or unusable.
mdate-sh
version.texi file. It examines
a file and prints some date information about it.
missing
missing
prints an informative warning and attempts to fix things so that the
build can continue.
mkinstalldirs
mkdir -p is not portable.
py-compile
texinfo.tex
make dvi, make ps
and make pdf to work when Texinfo sources are in the package.
ylwrap
lex and yacc and ensures that, for
instance, multiple yacc instances can be invoked in a single
directory in parallel.
Let's suppose you just finished writing zardoz, a program to make
your head float from vortex to vortex. You've been using Autoconf to
provide a portability framework, but your Makefile.ins have been
ad-hoc. You want to make them bulletproof, so you turn to Automake.
The first step is to update your configure.in to include the
commands that automake needs. The way to do this is to add an
AM_INIT_AUTOMAKE call just after AC_INIT:
AC_INIT(zardoz, 1.0)
AM_INIT_AUTOMAKE
...
Since your program doesn't have any complicating factors (e.g., it
doesn't use gettext, it doesn't want to build a shared library),
you're done with this part. That was easy!
Now you must regenerate configure. But to do that, you'll need
to tell autoconf how to find the new macro you've used. The
easiest way to do this is to use the aclocal program to generate
your aclocal.m4 for you. But wait... maybe you already have an
aclocal.m4, because you had to write some hairy macros for your
program. The aclocal program lets you put your own macros into
acinclude.m4, so simply rename and then run:
mv aclocal.m4 acinclude.m4
aclocal
autoconf
Now it is time to write your Makefile.am for zardoz.
Since zardoz is a user program, you want to install it where the
rest of the user programs go: bindir. Additionally,
zardoz has some Texinfo documentation. Your configure.in
script uses AC_REPLACE_FUNCS, so you need to link against
$(LIBOBJS). So here's what you'd write:
bin_PROGRAMS = zardoz
zardoz_SOURCES = main.c head.c float.c vortex9.c gun.c
zardoz_LDADD = $(LIBOBJS)
info_TEXINFOS = zardoz.texi
Now you can run automake --add-missing to generate your
Makefile.in and grab any auxiliary files you might need, and
you're done!
Of course, GNU Hello is somewhat more featureful than your traditional two-liner. GNU Hello is internationalized, does option processing, and has a manual and a test suite.
Here is the configure.in from GNU Hello.
Please note: The calls to AC_INIT and AM_INIT_AUTOMAKE
in this example use a deprecated syntax. For the current approach,
see the description of AM_INIT_AUTOMAKE in Public macros.
dnl Process this file with autoconf to produce a configure script.
AC_INIT(src/hello.c)
AM_INIT_AUTOMAKE(hello, 1.3.11)
AM_CONFIG_HEADER(config.h)
dnl Set of available languages.
ALL_LINGUAS="de fr es ko nl no pl pt sl sv"
dnl Checks for programs.
AC_PROG_CC
AC_ISC_POSIX
dnl Checks for libraries.
dnl Checks for header files.
AC_STDC_HEADERS
AC_HAVE_HEADERS(string.h fcntl.h sys/file.h sys/param.h)
dnl Checks for library functions.
AC_FUNC_ALLOCA
dnl Check for st_blksize in struct stat
AC_ST_BLKSIZE
dnl internationalization macros
AM_GNU_GETTEXT
AC_OUTPUT([Makefile doc/Makefile intl/Makefile po/Makefile.in \
src/Makefile tests/Makefile tests/hello],
[chmod +x tests/hello])
The AM_ macros are provided by Automake (or the Gettext library);
the rest are standard Autoconf macros.
The top-level Makefile.am:
EXTRA_DIST = BUGS ChangeLog.O
SUBDIRS = doc intl po src tests
As you can see, all the work here is really done in subdirectories.
The po and intl directories are automatically generated
using gettextize; they will not be discussed here.
In doc/Makefile.am we see:
info_TEXINFOS = hello.texi
hello_TEXINFOS = gpl.texi
This is sufficient to build, install, and distribute the GNU Hello manual.
Here is tests/Makefile.am:
TESTS = hello
EXTRA_DIST = hello.in testdata
The script hello is generated by configure, and is the
only test case. make check will run this test.
Last we have src/Makefile.am, where all the real work is done:
bin_PROGRAMS = hello
hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h
hello_LDADD = @INTLLIBS@ @ALLOCA@
localedir = $(datadir)/locale
INCLUDES = -I../intl -DLOCALEDIR=\"$(localedir)\"
Here is another, trickier example. It shows how to generate two
programs (true and false) from the same source file
(true.c). The difficult part is that each compilation of
true.c requires different cpp flags.
bin_PROGRAMS = true false
false_SOURCES =
false_LDADD = false.o
true.o: true.c
$(COMPILE) -DEXIT_CODE=0 -c true.c
false.o: true.c
$(COMPILE) -DEXIT_CODE=1 -o false.o -c true.c
Note that there is no true_SOURCES definition. Automake will
implicitly assume that there is a source file named true.c, and
define rules to compile true.o and link true. The
true.o: true.c rule supplied by the above Makefile.am,
will override the Automake generated rule to build true.o.
false_SOURCES is defined to be empty--that way no implicit value
is substituted. Because we have not listed the source of
false, we have to tell Automake how to link the program. This is
the purpose of the false_LDADD line. A false_DEPENDENCIES
variable, holding the dependencies of the false target will be
automatically generated by Automake from the content of
false_LDADD.
The above rules won't work if your compiler doesn't accept both
-c and -o. The simplest fix for this is to introduce a
bogus dependency (to avoid problems with a parallel make):
true.o: true.c false.o
$(COMPILE) -DEXIT_CODE=0 -c true.c
false.o: true.c
$(COMPILE) -DEXIT_CODE=1 -c true.c && mv true.o false.o
Also, these explicit rules do not work if the de-ANSI-fication feature is used (see ANSI). Supporting de-ANSI-fication requires a little more work:
true._o: true._c false.o
$(COMPILE) -DEXIT_CODE=0 -c true.c
false._o: true._c
$(COMPILE) -DEXIT_CODE=1 -c true.c && mv true._o false.o
As it turns out, there is also a much easier way to do this same task.
Some of the above techniques are useful enough that we've kept the
example in the manual. However if you were to build true and
false in real life, you would probably use per-program
compilation flags, like so:
bin_PROGRAMS = false true
false_SOURCES = true.c
false_CPPFLAGS = -DEXIT_CODE=1
true_SOURCES = true.c
true_CPPFLAGS = -DEXIT_CODE=0
In this case Automake will cause true.c to be compiled twice,
with different flags. De-ANSI-fication will work automatically. In
this instance, the names of the object files would be chosen by
automake; they would be false-true.o and true-true.o.
(The name of the object files rarely matters.)
Makefile.inTo create all the Makefile.ins for a package, run the
automake program in the top level directory, with no arguments.
automake will automatically find each appropriate
Makefile.am (by scanning configure.in; see configure)
and generate the corresponding Makefile.in. Note that
automake has a rather simplistic view of what constitutes a
package; it assumes that a package has only one configure.in, at
the top. If your package has multiple configure.ins, then you
must run automake in each directory holding a
configure.in. (Alternatively, you may rely on Autoconf's
autoreconf, which is able to recurse your package tree and run
automake where appropriate.)
You can optionally give automake an argument; .am is
appended to the argument and the result is used as the name of the input
file. This feature is generally only used to automatically rebuild an
out-of-date Makefile.in. Note that automake must always
be run from the topmost directory of a project, even if being used to
regenerate the Makefile.in in some subdirectory. This is
necessary because automake must scan configure.in, and
because automake uses the knowledge that a Makefile.in is
in a subdirectory to change its behavior in some cases.
Automake will run autoconf to scan configure.in and its
dependencies (aclocal.m4), therefore autoconf must be in
your PATH. If there is an AUTOCONF variable in your
environment it will be used instead of autoconf, this allows you
to select a particular version of Autoconf. By the way, don't
misunderstand this paragraph: Automake runs autoconf to
scan your configure.in, this won't build
configure and you still have to run autoconf yourself for
this purpose.
automake accepts the following options:
-a
--add-missing
config.guess is required if configure.in runs
AC_CANONICAL_HOST. Automake is distributed with several of these
files (see Auxiliary Programs); this option will cause the missing
ones to be automatically added to the package, whenever possible. In
general if Automake tells you a file is missing, try using this option.
By default Automake tries to make a symbolic link pointing to its own
copy of the missing file; this can be changed with --copy.
Many of the potentially-missing files are common scripts whose
location may be specified via the AC_CONFIG_AUX_DIR macro.
Therefore, AC_CONFIG_AUX_DIR's setting affects whether a
file is considered missing, and where the missing file is added
(see Optional).
--libdir=dir-c
--copy
--add-missing, causes installed files to be
copied. The default is to make a symbolic link.
--cygnus
Makefile.ins to follow Cygnus rules, instead
of GNU or Gnits rules. For more information, see Cygnus.
-f
--force-missing
--add-missing, causes standard files to be reinstalled
even if they already exist in the source tree. This involves removing
the file from the source tree before creating the new symlink (or, with
--copy, copying the new file).
--foreign
foreign. For more information, see
Strictness.
--gnits
gnits. For more information, see
Gnits.
--gnu
gnu. For more information, see
Gnits. This is the default strictness.
--help
-i
--ignore-deps
Makefiles; see Dependencies.
--include-deps
--no-force
automake creates all Makefile.ins mentioned in
configure.in. This option causes it to only update those
Makefile.ins which are out of date with respect to one of their
dependents.
Due to a bug in its implementation, this option is currently ignored.
It will be fixed in Automake 1.8.
-o dir--output-dir=dirMakefile.in in the directory dir.
Ordinarily each Makefile.in is created in the directory of the
corresponding Makefile.am. This option is deprecated and will be
removed in a future release.
-v
--verbose
--version
-W CATEGORY
--warnings=categorygnu
obsolete
portability
syntax
unsupported
all
none
error
A category can be turned off by prefixing its name with no-. For
instance -Wno-syntax will hide the warnings about unused
variables.
The categories output by default are syntax and
unsupported. Additionally, gnu is enabled in --gnu and
--gnits strictness.
portability warnings are currently disabled by default, but they
will be enabled in --gnu and --gnits strictness in a
future release.
The environment variable WARNINGS can contain a comma separated
list of categories to enable. It will be taken into account before the
command-line switches, this way -Wnone will also ignore any
warning category enabled by WARNINGS. This variable is also used
by other tools like autoconf; unknown categories are ignored
for this reason.
configure.inAutomake scans the package's configure.in to determine certain
information about the package. Some autoconf macros are required
and some variables must be defined in configure.in. Automake
will also use information from configure.in to further tailor its
output.
Automake also supplies some Autoconf macros to make the maintenance
easier. These macros can automatically be put into your
aclocal.m4 using the aclocal program.
The one real requirement of Automake is that your configure.in
call AM_INIT_AUTOMAKE. This macro does several things which are
required for proper Automake operation (see Macros).
Here are the other macros which Automake requires but which are not run
by AM_INIT_AUTOMAKE:
AC_CONFIG_FILES
AC_OUTPUT
Makefile if there
exists a file with the same name and the .am extension appended.
Typically, AC_CONFIG_FILES([foo/Makefile]) will cause Automake to
generate foo/Makefile.in if foo/Makefile.am exists.
These files are all removed by make distclean.
Every time Automake is run it calls Autoconf to trace
configure.in. This way it can recognize the use of certain
macros and tailor the generated Makefile.in appropriately.
Currently recognized macros and their effects are:
AC_CONFIG_HEADERS
AM_CONFIG_HEADER
(see Macros); this is no longer the case today.
AC_CONFIG_AUX_DIR
mkinstalldirs, in the directory named in this macro invocation.
(The full list of scripts is: config.guess, config.sub,
depcomp, elisp-comp, compile, install-sh,
ltmain.sh, mdate-sh, missing, mkinstalldirs,
py-compile, texinfo.tex, and ylwrap.) Not all
scripts are always searched for; some scripts will only be sought if the
generated Makefile.in requires them.
If AC_CONFIG_AUX_DIR is not given, the scripts are looked for in
their standard locations. For mdate-sh,
texinfo.tex, and ylwrap, the standard location is the
source directory corresponding to the current Makefile.am. For
the rest, the standard location is the first one of ., ..,
or ../.. (relative to the top source directory) that provides any
one of the helper scripts. See Finding `configure' Input.
Required files from AC_CONFIG_AUX_DIR are automatically
distributed, even if there is no Makefile.am in this directory.
AC_CANONICAL_HOST
config.guess and config.sub
exist. Also, the Makefile variables host_alias and
host_triplet are introduced. See Getting the Canonical System Type.
AC_CANONICAL_SYSTEM
AC_CANONICAL_HOST, but also defines the
Makefile variables build_alias and target_alias.
See Getting the Canonical System Type.
AC_LIBSOURCE
AC_LIBSOURCES
AC_LIBOBJ
AC_LIBSOURCE or AC_LIBSOURCES.
Note that the AC_LIBOBJ macro calls AC_LIBSOURCE. So if
an Autoconf macro is documented to call AC_LIBOBJ([file]), then
file.c will be distributed automatically by Automake. This
encompasses many macros like AC_FUNC_ALLOCA,
AC_FUNC_MEMCMP, AC_REPLACE_FUNCS, and others.
By the way, direct assignments to LIBOBJS are no longer
supported. You should always use AC_LIBOBJ for this purpose.
See AC_LIBOBJ vs. LIBOBJS.
AC_PROG_RANLIB
AC_PROG_CXX
AC_PROG_F77
AC_F77_LIBRARY_LDFLAGS
AC_PROG_LIBTOOL
libtool (see Introduction).
AC_PROG_YACC
YACC in configure.in. The former is
preferred (see Particular Program Checks).
AC_PROG_LEX
AC_SUBST
Makefile.in. See Setting Output Variables.
If the Autoconf manual says that a macro calls AC_SUBST for
var, or defined the output variable var then var will
be defined in each generated Makefile.in.
E.g. AC_PATH_XTRA defines X_CFLAGS and X_LIBS, so
you can use the variable in any Makefile.am if
AC_PATH_XTRA is called.
AM_C_PROTOTYPES
AM_GNU_GETTEXT
AM_MAINTAINER_MODE
--enable-maintainer-mode option to
configure. If this is used, automake will cause
maintainer-only rules to be turned off by default in the
generated Makefile.ins. This macro defines the
MAINTAINER_MODE conditional, which you can use in your own
Makefile.am.
Automake includes a number of Autoconf macros which can be used in your
package; some of them are actually required by Automake in certain
situations. These macros must be defined in your aclocal.m4;
otherwise they will not be seen by autoconf.
The aclocal program will automatically generate aclocal.m4
files based on the contents of configure.in. This provides a
convenient way to get Automake-provided macros, without having to
search around. Also, the aclocal mechanism allows other packages
to supply their own macros.
At startup, aclocal scans all the .m4 files it can find,
looking for macro definitions (see Macro search path). Then it
scans configure.in. Any
mention of one of the macros found in the first step causes that macro,
and any macros it in turn requires, to be put into aclocal.m4.
The contents of acinclude.m4, if it exists, are also
automatically included in aclocal.m4. This is useful for
incorporating local macros into configure.
aclocal tries to be smart about looking for new AC_DEFUNs
in the files it scans. It also
tries to copy the full text of the scanned file into aclocal.m4,
including both # and dnl comments. If you want to make a
comment which will be completely ignored by aclocal, use
## as the comment leader.
aclocal accepts the following options:
--acdir=dir--help
-I dir.m4 files.
--output=fileaclocal.m4.
--print-ac-dir
aclocal will search to
find third-party .m4 files. When this option is given, normal
processing is suppressed. This option can be used by a package to
determine where to install a macro file.
--verbose
--version
By default, aclocal searches for .m4 files in the following
directories, in this order:
.m4 macros distributed with automake itself
are stored. APIVERSION depends on the automake release used;
for automake 1.6.x, APIVERSION = 1.6.
.m4 files, and is
configured when automake itself is built. This is
@datadir@/aclocal/, which typically
expands to ${prefix}/share/aclocal/. To find the compiled-in
value of acdir, use the --print-ac-dir option
(see aclocal options).
As an example, suppose that automake-1.6.2 was configured with
--prefix=/usr/local. Then, the search path would be:
/usr/local/share/aclocal-1.6/
/usr/local/share/aclocal/
As explained in (see aclocal options), there are several options that can be used to change or extend this search path.
--acdir
The most obvious option to modify the search path is
--acdir=dir, which changes default directory and
drops the APIVERSION directory. For example, if one specifies
--acdir=/opt/private/, then the search path becomes:
/opt/private/
Note that this option, --acdir, is intended for use
by the internal automake test suite only; it is not ordinarily
needed by end-users.
-I dirAny extra directories specified using -I options
(see aclocal options) are prepended to this search list. Thus,
aclocal -I /foo -I /bar results in the following search path:
/foo
/bar
dirlist
There is a third mechanism for customizing the search path. If a
dirlist file exists in acdir, then that file is assumed to
contain a list of directories, one per line, to be added to the search
list. These directories are searched after all other
directories.
For example, suppose
acdir/dirlist contains the following:
/test1
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and that aclocal was called with the -I /foo -I /bar options.
Then, the search path would be
/foo
/bar
/test1
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If the --acdir=dir option is used, then aclocal
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--acdir=/opt/private/ example above, aclocal would look
for /opt/private/dirlist. Again, however, the --acdir
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--acdir is not ordinarily needed by end-users.
dirlist is useful in the following situation: suppose that
automake version 1.6.2 is installed with
$prefix=/usr by the system vendor. Thus, the default search
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/usr/share/aclocal-1.6/
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However, suppose further that many packages have been manually
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In that case, many of these "extra" .m4 files are in
/usr/local/share/aclocal. The only way to force
/usr/bin/aclocal to find these "extra" .m4 files
is to always call aclocal -I /usr/local/share/aclocal.
This is inconvenient. With dirlist, one may create the file
/usr/share/aclocal/dirlist
which contains only the single line
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Now, the "default" search path on the affected system is
/usr/share/aclocal-1.6/
/usr/share/aclocal/
/usr/local/share/aclocal/
without the need for -I options; -I options can be reserved
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Automake ships with several Autoconf macros that you can use from your
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See Multilibs.
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AM_INIT_AUTOMAKE
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HP-UX 10 is one such system.
AM_PROG_GCJ
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GCJ and GCJFLAGS. gcj is the Java front-end to the
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AM_SYS_POSIX_TERMIOS
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--with-regex to the configure command line. If
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The following macros are private macros you should not call directly. They are called by the other public macros when appropriate. Do not rely on them, as they might be changed in a future version. Consider them as implementation details; or better, do not consider them at all: skip this section!
_AM_DEPENDENCIES
AM_SET_DEPDIR
AM_DEP_TRACK
AM_OUTPUT_DEPENDENCY_COMMANDS
AM_MAKE_INCLUDE
make handles
include statements. This macro is automatically invoked when
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AM_PROG_INSTALL_STRIP
install which can be used to
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AM_SANITY_CHECK
AM_INIT_AUTOMAKE.
The aclocal program doesn't have any built-in knowledge of any
macros, so it is easy to extend it with your own macros.
This can be used by libraries which want to supply their own Autoconf
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installs this macro so that aclocal will find it.
A macro file's name should end in .m4. Such files should be
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aclocaldir = $(datadir)/aclocal
aclocal_DATA = mymacro.m4 myothermacro.m4
A file of macros should be a series of properly quoted
AC_DEFUN's (see Macro Definitions). The aclocal programs also understands
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Each file should have no side effects but macro definitions.
Especially, any call to AC_PREREQ should be done inside the
defined macro, not at the beginning of the file.
Starting with Automake 1.8, aclocal will warn about all
underquoted calls to AC_DEFUN. We realize this will annoy a
lot of people, because aclocal was not so strict in the past
and many third party macros are underquoted; and we have to apologize
for this temporary inconvenience. The reason we have to be stricter
is that a future implementation of aclocal will have to
temporary include all these third party .m4 files, maybe
several times, even those which are not actually needed. Doing so
should alleviate many problem of the current implementation, however
it requires a stricter style from the macro authors. Hopefully it is
easy to revise the existing macros. For instance
# bad style
AC_PREREQ(2.57)
AC_DEFUN(AX_FOOBAR,
[AC_REQUIRE([AX_SOMETHING])dnl
AX_FOO
AX_BAR
])
should be rewritten as
AC_DEFUN([AX_FOOBAR],
[AC_PREREQ(2.57)dnl
AC_REQUIRE([AX_SOMETHING])dnl
AX_FOO
AX_BAR
])
Wrapping the AC_PREREQ call inside the macro ensures that
Autoconf 2.57 will not be required if AX_FOOBAR is not actually
used. Most importantly, quoting the first argument of AC_DEFUN
allows the macro to be redefined or included twice (otherwise this
first argument would be expansed during the second definition).
If you have been directed here by the aclocal diagnostic but
are not the maintainer of the implicated macro, you will want to
contact the maintainer of that macro. Please make sure you have the
last version of the macro and that the problem already hasn't been
reported before doing so: people tend to work faster when they aren't
flooded by mails.
Makefile.amIn packages with subdirectories, the top level Makefile.am must
tell Automake which subdirectories are to be built. This is done via
the SUBDIRS variable.
The SUBDIRS variable holds a list of subdirectories in which
building of various sorts can occur. Many targets (e.g. all) in
the generated Makefile will run both locally and in all specified
subdirectories. Note that the directories listed in SUBDIRS are
not required to contain Makefile.ams; only Makefiles
(after configuration). This allows inclusion of libraries from packages
which do not use Automake (such as gettext).
In packages that use subdirectories, the top-level Makefile.am is
often very short. For instance, here is the Makefile.am from the
GNU Hello distribution:
EXTRA_DIST = BUGS ChangeLog.O README-alpha
SUBDIRS = doc intl po src tests
When Automake invokes make in a subdirectory, it uses the value
of the MAKE variable. It passes the value of the variable
AM_MAKEFLAGS to the make invocation; this can be set in
Makefile.am if there are flags you must always pass to
make.
The directories mentioned in SUBDIRS must be direct children of
the current directory. For instance, you cannot put src/subdir
into SUBDIRS. Instead you should put SUBDIRS = subdir
into src/Makefile.am. Automake can be used to construct packages
of arbitrary depth this way.
By default, Automake generates Makefiles which work depth-first
(postfix). However, it is possible to change this ordering. You
can do this by putting . into SUBDIRS. For instance,
putting . first will cause a prefix ordering of
directories. All clean targets are run in reverse order of build
targets.
It is possible to define the SUBDIRS variable conditionally if,
like in the case of GNU Inetutils, you want to only build a
subset of the entire package.
To illustrate how this works, let's assume we have two directories
src/ and opt/. src/ should always be built, but we
want to decide in ./configure whether opt/ will be built
or not. (For this example we will assume that opt/ should be
built when the variable $want_opt was set to yes.)
Running make should thus recurse into src/ always, and
then maybe in opt/.
However make dist should always recurse into both src/ and
opt/. Because opt/ should be distributed even if it is
not needed in the current configuration. This means opt/Makefile
should be created unconditionally. 3
There are two ways to setup a project like this. You can use Automake
conditionals (see Conditionals) or use Autoconf AC_SUBST
variables (see Setting Output Variables). Using Automake conditionals is the
preferred solution.
AM_CONDITIONAL
configure should output the Makefile for each directory
and define a condition into which opt/ should be built.
...
AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes])
AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
...
Then SUBDIRS can be defined in the top-level Makefile.am
as follows.
if COND_OPT
MAYBE_OPT = opt
endif
SUBDIRS = src $(MAYBE_OPT)
As you can see, running make will rightly recurse into
src/ and maybe opt/.
As you can't see, running make dist will recurse into both
src/ and opt/ directories because make dist, unlike
make all, doesn't use the SUBDIRS variable. It uses the
DIST_SUBDIRS variable.
In this case Automake will define DIST_SUBDIRS = src opt
automatically because it knows that MAYBE_OPT can contain
opt in some condition.
AC_SUBST
Another idea is to define MAYBE_OPT from ./configure using
AC_SUBST:
...
if test "$want_opt" = yes; then
MAYBE_OPT=opt
else
MAYBE_OPT=
fi
AC_SUBST([MAYBE_OPT])
AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
...
In this case the top-level Makefile.am should look as follows.
SUBDIRS = src $(MAYBE_OPT)
DIST_SUBDIRS = src opt
The drawback is that since Automake cannot guess what the possible
values of MAYBE_OPT are, it is necessary to define
DIST_SUBDIRS.
DIST_SUBDIRS is used
As shown in the above examples, DIST_SUBDIRS is used by targets
that need to recurse in all directories, even those which have been
conditionally left out of the build.
Precisely, DIST_SUBDIRS is used by make dist, make
distclean, and make maintainer-clean. All other recursive
targets use SUBDIRS.
Automake will define DIST_SUBDIRS automatically from the
possibles values of SUBDIRS in all conditions.
If SUBDIRS contains AC_SUBST variables,
DIST_SUBDIRS will not be defined correctly because Automake
doesn't know the possible values of these variables. In this case
DIST_SUBDIRS needs to be defined manually.
If you've ever read Peter Miller's excellent paper,
Recursive Make Considered Harmful, the preceding section on the use of
subdirectories will probably come as unwelcome advice. For those who
haven't read the paper, Miller's main thesis is that recursive
make invocations are both slow and error-prone.
Automake provides sufficient cross-directory support 4 to enable you
to write a single Makefile.am for a complex multi-directory
package.
By default an installable file specified in a subdirectory will have its
directory name stripped before installation. For instance, in this
example, the header file will be installed as
$(includedir)/stdio.h:
include_HEADERS = inc/stdio.h
However, the nobase_ prefix can be used to circumvent this path
stripping. In this example, the header file will be installed as
$(includedir)/sys/types.h:
nobase_include_HEADERS = sys/types.h
nobase_ should be specified first when used in conjunction with
either dist_ or nodist_ (see Dist). For instance:
nobase_dist_pkgdata_DATA = images/vortex.pgm
Automake generates rules to automatically rebuild Makefiles,
configure, and other derived files like Makefile.in.
If you are using AM_MAINTAINER_MODE in configure.in, then
these automatic rebuilding rules are only enabled in maintainer mode.
Sometimes you need to run aclocal with an argument like -I
to tell it where to find .m4 files. Since sometimes make
will automatically run aclocal, you need a way to specify these
arguments. You can do this by defining ACLOCAL_AMFLAGS; this
holds arguments which are passed verbatim to aclocal. This variable
is only useful in the top-level Makefile.am.
A large part of Automake's functionality is dedicated to making it easy to build programs and libraries.
In order to build a program, you need to tell Automake which sources are part of it, and which libraries it should be linked with.
This section also covers conditional compilation of sources or programs. Most of the comments about these also apply to libraries (see A Library) and libtool libraries (see A Shared Library).
In a directory containing source that gets built into a program (as
opposed to a library or a script), the PROGRAMS primary is used.
Programs can be installed in bindir, sbindir,
libexecdir, pkglibdir, or not at all (noinst).
They can also be built only for make check, in which case the
prefix is check.
For instance:
bin_PROGRAMS = hello
In this simple case, the resulting Makefile.in will contain code
to generate a program named hello.
Associated with each program are several assisting variables which are named after the program. These variables are all optional, and have reasonable defaults. Each variable, its use, and default is spelled out below; we use the "hello" example throughout.
The variable hello_SOURCES is used to specify which source files
get built into an executable:
hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h
This causes each mentioned .c file to be compiled into the
corresponding .o. Then all are linked to produce hello.
If hello_SOURCES is not specified, then it defaults to the single
file hello.c; that is, the default is to compile a single C file
whose base name is the name of the program itself. (This is a terrible
default but we are stuck with it for historical reasons.)
Multiple programs can be built in a single directory. Multiple programs
can share a single source file, which must be listed in each
_SOURCES definition.
Header files listed in a _SOURCES definition will be included in
the distribution but otherwise ignored. In case it isn't obvious, you
should not include the header file generated by configure in a
_SOURCES variable; this file should not be distributed. Lex
(.l) and Yacc (.y) files can also be listed; see Yacc and Lex.
If you need to link against libraries that are not found by
configure, you can use LDADD to do so. This variable is
used to specify additional objects or libraries to link with; it is
inappropriate for specifying specific linker flags, you should use
AM_LDFLAGS for this purpose.
Sometimes, multiple programs are built in one directory but do not share
the same link-time requirements. In this case, you can use the
prog_LDADD variable (where prog is the name of the
program as it appears in some _PROGRAMS variable, and usually
written in lowercase) to override the global LDADD. If this
variable exists for a given program, then that program is not linked
using LDADD.
For instance, in GNU cpio, pax, cpio and mt are
linked against the library libcpio.a. However, rmt is
built in the same directory, and has no such link requirement. Also,
mt and rmt are only built on certain architectures. Here
is what cpio's src/Makefile.am looks like (abridged):
bin_PROGRAMS = cpio pax @MT@
libexec_PROGRAMS = @RMT@
EXTRA_PROGRAMS = mt rmt
LDADD = ../lib/libcpio.a @INTLLIBS@
rmt_LDADD =
cpio_SOURCES = ...
pax_SOURCES = ...
mt_SOURCES = ...
rmt_SOURCES = ...
prog_LDADD is inappropriate for passing program-specific
linker flags (except for -l, -L, -dlopen and
-dlpreopen). So, use the prog_LDFLAGS variable for
this purpose.
It is also occasionally useful to have a program depend on some other
target which is not actually part of that program. This can be done
using the prog_DEPENDENCIES variable. Each program depends
on the contents of such a variable, but no further interpretation is
done.
If prog_DEPENDENCIES is not supplied, it is computed by
Automake. The automatically-assigned value is the contents of
prog_LDADD, with most configure substitutions, -l,
-L, -dlopen and -dlpreopen options removed. The
configure substitutions that are left in are only @LIBOBJS@ and
@ALLOCA@; these are left because it is known that they will not
cause an invalid value for prog_DEPENDENCIES to be
generated.
You can't put a configure substitution (e.g., @FOO@) into a
_SOURCES variable. The reason for this is a bit hard to explain,
but suffice to say that it simply won't work. Automake will give an
error if you try to do this.
Fortunately there are two other ways to achieve the same result. One is
to use configure substitutions in _LDADD variables, the other is
to use an Automake conditional.
_LDADD substitutions
Automake must know all the source files that could possibly go into a
program, even if not all the files are built in every circumstance. Any
files which are only conditionally built should be listed in the
appropriate EXTRA_ variable. For instance, if
hello-linux.c or hello-generic.c were conditionally included
in hello, the Makefile.am would contain:
bin_PROGRAMS = hello
hello_SOURCES = hello-common.c
EXTRA_hello_SOURCES = hello-linux.c hello-generic.c
hello_LDADD = @HELLO_SYSTEM@
hello_DEPENDENCIES = @HELLO_SYSTEM@
You can then setup the @HELLO_SYSTEM@ substitution from
configure.in:
...
case $host in
*linux*) HELLO_SYSTEM='hello-linux.$(OBJEXT)' ;;
*) HELLO_SYSTEM='hello-generic.$(OBJEXT)' ;;
esac
AC_SUBST([HELLO_SYSTEM])
...
In this case, HELLO_SYSTEM should be replaced by
hello-linux.o or hello-bsd.o, and added to
hello_DEPENDENCIES and hello_LDADD in order to be built
and linked in.
An often simpler way to compile source files conditionally is to use
Automake conditionals. For instance, you could use this
Makefile.am construct to build the same hello example:
bin_PROGRAMS = hello
if LINUX
hello_SOURCES = hello-linux.c hello-common.c
else
hello_SOURCES = hello-generic.c hello-common.c
endif
In this case, your configure.in should setup the LINUX
conditional using AM_CONDITIONAL (see Conditionals).
When using conditionals like this you don't need to use the
EXTRA_ variable, because Automake will examine the contents of
each variable to construct the complete list of source files.
If your program uses a lot of files, you will probably prefer a
conditional +=.
bin_PROGRAMS = hello
hello_SOURCES = hello-common.c
if LINUX
hello_SOURCES += hello-linux.c
else
hello_SOURCES += hello-generic.c
endif
Sometimes it is useful to determine the programs that are to be built
at configure time. For instance, GNU cpio only builds
mt and rmt under special circumstances. The means to
achieve conditional compilation of programs are the same you can use
to compile source files conditionally: substitutions or conditionals.
configure substitutions
In this case, you must notify Automake of all the programs that can
possibly be built, but at the same time cause the generated
Makefile.in to use the programs specified by configure.
This is done by having configure substitute values into each
_PROGRAMS definition, while listing all optionally built programs
in EXTRA_PROGRAMS.
bin_PROGRAMS = cpio pax $(MT)
libexec_PROGRAMS = $(RMT)
EXTRA_PROGRAMS = mt rmt
As explained in EXEEXT, Automake will rewrite
bin_PROGRAMS, libexec_PROGRAMS, and
EXTRA_PROGRAMS, appending $(EXEEXT) to each binary.
Obviously it cannot rewrite values obtained at run-time through
configure substitutions, therefore you should take care of
appending $(EXEEXT) yourself, as in AC_SUBST([MT],
['mt${EXEEXT}']).
You can also use Automake conditionals (see Conditionals) to
select programs to be built. In this case you don't have to worry
about $(EXEEXT) or EXTRA_PROGRAMS.
bin_PROGRAMS = cpio pax
if WANT_MT
bin_PROGRAMS += mt
endif
if WANT_RMT
libexec_PROGRAMS = rmt
endif
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.
See 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
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 (see Canonicalization), so the _SOURCES
variable corresponding to liblob.a is liblob_a_SOURCES,
not liblob.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
(see Sources).
Building shared libraries portably is a relatively complex matter. For this reason, GNU Libtool (see Introduction) was created to help build shared libraries in a platform-independent way.
Libtool abstracts shared and static libraries into a unified
concept henceforth called libtool libraries. Libtool libraries
are files using the .la suffix, and can designate a static
library, a shared library, or maybe both. Their exact nature cannot
be determined until ./configure is run: not all platforms
support all kinds of libraries, and users can explicitly select which
libraries should be built. (However the package's maintainers can
tune the default, See The AC_PROG_LIBTOOL macro.)
Because object files for shared and static libraries must be compiled
differently, libtool is also used during compilation. Object files
built by libtool are called libtool objects: these are files
using the .lo suffix. Libtool libraries are built from these
libtool objects.
You should not assume anything about the structure of .la or
.lo files and how libtool constructs them: this is libtool's
concern, and the last thing one wants is to learn about libtool's
guts. However the existence of these files matters, because they are
used as targets and dependencies in Makefiles when building
libtool libraries. There are situations where you may have to refer
to these, for instance when expressing dependencies for building
source files conditionally (see Conditional Libtool Sources).
People considering writing a plug-in system, with dynamically loaded
modules, should look into libltdl: libtool's dlopening library
(see Using libltdl).
This offers a portable dlopening facility to load libtool libraries
dynamically, and can also achieve static linking where unavoidable.
Before we discuss how to use libtool with Automake in details, it should be noted that the libtool manual also has a section about how to use Automake with libtool (see Using Automake with Libtool).
Automake uses libtool to build libraries declared with the
LTLIBRARIES primary. Each _LTLIBRARIES variable is a
list of libtool libraries to build. For instance, to create a libtool
library named libgettext.la, and install it in libdir,
write:
lib_LTLIBRARIES = libgettext.la
libgettext_la_SOURCES = gettext.c gettext.h ...
Automake predefines the variable pkglibdir, so you can use
pkglib_LTLIBRARIES to install libraries in
$(libdir)/@PACKAGE@/.
Like conditional programs (see Conditional Programs), there are
two main ways to build conditional libraries: using Automake
conditionals or using Autoconf AC_SUBSTitutions.
The important implementation detail you have to be aware of is that
the place where a library will be installed matters to libtool: it
needs to be indicated at link-time using the -rpath
option.
For libraries whose destination directory is known when Automake runs,
Automake will automatically supply the appropriate -rpath
option to libtool. This is the case for libraries listed explicitly in
some installable _LTLIBRARIES variables such as
lib_LTLIBRARIES.
However, for libraries determined at configure time (and thus
mentioned in EXTRA_LTLIBRARIES), Automake does not know the
final installation directory. For such libraries you must add the
-rpath option to the appropriate _LDFLAGS variable by
hand.
The examples below illustrate the differences between these two methods.
Here is an example where $(WANTEDLIBS) is an AC_SUBSTed
variable set at ./configure-time to either libfoo.la,
libbar.la, both, or none. Although $(WANTEDLIBS)
appears in the lib_LTLIBRARIES, Automake cannot guess it
relates to libfoo.la or libbar.la by the time it creates
the link rule for these two libraries. Therefore the -rpath
argument must be explicitly supplied.
EXTRA_LTLIBRARIES = libfoo.la libbar.la
lib_LTLIBRARIES = $(WANTEDLIBS)
libfoo_la_SOURCES = foo.c ...
libfoo_la_LDFLAGS = -rpath '$(libdir)'
libbar_la_SOURCES = bar.c ...
libbar_la_LDFLAGS = -rpath '$(libdir)'
Here is how the same Makefile.am would look using Automake
conditionals named WANT_LIBFOO and WANT_LIBBAR. Now
Automake is able to compute the -rpath setting itself, because
it's clear that both libraries will end up in $(libdir) if they
are installed.
lib_LTLIBRARIES =
if WANT_LIBFOO
lib_LTLIBRARIES += libfoo.la
endif
if WANT_LIBBAR
lib_LTLIBRARIES += libbar.la
endif
libfoo_la_SOURCES = foo.c ...
libbar_la_SOURCES = bar.c ...
Conditional compilation of sources in a library can be achieved in the
same way as conditional compilation of sources in a program
(see Conditional Sources). The only difference is that
_LIBADD should be used instead of _LDADD and that it
should mention libtool objects (.lo files).
So, to mimic the hello example from Conditional Sources,
we could build a libhello.la library using either
hello-linux.c or hello-generic.c with the following
Makefile.am.
lib_LTLIBRARIES = libhello.la
libhello_la_SOURCES = hello-common.c
EXTRA_libhello_la_SOURCES = hello-linux.c hello-generic.c
libhello_la_LIBADD = $(HELLO_SYSTEM)
libhello_la_DEPENDENCIES = $(HELLO_SYSTEM)
And make sure $(HELLO_SYSTEM) is set to either
hello-linux.lo or hello-generic.lo in
./configure.
Or we could simply use an Automake conditional as follows.
lib_LTLIBRARIES = libhello.la
libhello_la_SOURCES = hello-common.c
if LINUX
libhello_la_SOURCES += hello-linux.c
else
libhello_la_SOURCES += hello-generic.c
endif
Sometimes you want to build libtool libraries which should not be installed. These are called libtool convenience libraries and are typically used to encapsulate many sublibraries, later gathered into one big installed library.
Libtool convenience libraries are declared by
noinst_LTLIBRARIES, check_LTLIBRARIES, or even
EXTRA_LTLIBRARIES. Unlike installed libtool libraries they do
not need an -rpath flag at link time (actually this is the only
difference).
Convenience libraries listed in noinst_LTLIBRARIES are always
built. Those listed in check_LTLIBRARIES are built only upon
make check. Finally, libraries listed in
EXTRA_LTLIBRARIES are never built explicitly: Automake outputs
rules to build them, but if the library does not appear as a Makefile
dependency anywhere it won't be built (this is why
EXTRA_LTLIBRARIES is used for conditional compilation).
Here is a sample setup merging libtool convenience libraries from
subdirectories into one main libtop.la library.
# -- Top-level Makefile.am --
SUBDIRS = sub1 sub2 ...
lib_LTLIBRARIES = libtop.la
libtop_la_SOURCES =
libtop_la_LIBADD = \
sub1/libsub1.la \
sub2/libsub2.la \
...
# -- sub1/Makefile.am --
noinst_LTLIBRARIES = libsub1.la
libsub1_la_SOURCES = ...
# -- sub2/Makefile.am --
# showing nested convenience libraries
SUBDIRS = sub2.1 sub2.2 ...
noinst_LTLIBRARIES = libsub2.la
libsub2_la_SOURCES =
libsub2_la_LIBADD = \
sub21/libsub21.la \
sub22/libsub22.la \
...
These are libtool libraries meant to be dlopened. They are
indicated to libtool by passing -module at link-time.
pkglib_LTLIBRARIES = mymodule.la
mymodule_la_SOURCES = doit.c
mymodule_LDFLAGS = -module
Ordinarily, Automake requires that a Library's name starts with
lib. However, when building a dynamically loadable module you
might wish to use a "nonstandard" name.
As shown in previous sections, the library_LIBADD
variable should be used to list extra libtool objects (.lo
files) or libtool libraries (.la) to add to library.
The library_LDFLAGS variable is the place to list
additional libtool flags, such as -version-info,
-static, and a lot more. See See Using libltdl.
LTLIBOBJS
Where an ordinary library might include $(LIBOBJS), a libtool
library must use $(LTLIBOBJS). This is required because the
object files that libtool operates on do not necessarily end in
.o.
Nowadays, the computation of LTLIBOBJS from LIBOBJS is
performed automatically by Autoconf (see AC_LIBOBJ vs. LIBOBJS).
required file `./ltmain.sh' not found
Libtool comes with a tool called libtoolize that will
install libtool's supporting files into a package. Running this
command will install ltmain.sh. You should execute it before
aclocal and automake.
People upgrading old packages to newer autotools are likely to face
this issue because older Automake versions used to call
libtoolize. Therefore old build scripts do not call
libtoolize.
Since Automake 1.6, it has been decided that running
libtoolize was none of Automake's business. Instead, that
functionality has been moved into the autoreconf command
(see Using autoreconf). If you do not want to remember what to run and
when, just learn the autoreconf command. Hopefully,
replacing existing bootstrap.sh or autogen.sh scripts by
a call to autoreconf should also free you from any similar
incompatible change in the future.
created with both libtool and without
Sometimes, the same source file is used both to build a libtool library and to build another non-libtool target (be it a program or another library).
Let's consider the following Makefile.am.
bin_PROGRAMS = prog
prog_SOURCES = prog.c foo.c ...
lib_LTLIBRARIES = libfoo.la
libfoo_la_SOURCES = foo.c ...
(In this trivial case the issue could be avoided by linking
libfoo.la with prog instead of listing foo.c in
prog_SOURCES. But let's assume we really want to keep
prog and libfoo.la separate.)
Technically, it means that we should build foo.$(OBJEXT) for
prog, and foo.lo for libfoo.la. The problem is
that in the course of creating foo.lo, libtool may erase (or
replace) foo.$(OBJEXT) - and this cannot be avoided.
Therefore, when Automake detects this situation it will complain with a message such as
object `foo.$(OBJEXT)' created both with libtool and without
A workaround for this issue is to ensure that these two objects get different basenames. As explained in renamed objects, this happens automatically when per-targets flags are used.
bin_PROGRAMS = prog
prog_SOURCES = prog.c foo.c ...
prog_CFLAGS = $(AM_CFLAGS)
lib_LTLIBRARIES = libfoo.la
libfoo_la_SOURCES = foo.c ...
Adding prog_CFLAGS = $(AM_CFLAGS) is almost a no-op, because
when the prog_CFLAGS is defined, it is used instead of
AM_CFLAGS. However as a side effect it will cause
prog.c and foo.c to be compiled as
prog-prog.$(OBJEXT) and prog-foo.$(OBJEXT) which solves
the issue.
Associated with each program are a collection of variables which can be used to modify how that program is built. There is a similar list of such variables for each library. The canonical name of the program (or library) is used as a base for naming these variables.
In the list below, we use the name "maude" to refer to the program or
library. In your Makefile.am you would replace this with the
canonical name of your program. This list also refers to "maude" as a
program, but in general the same rules apply for both static and dynamic
libraries; the documentation below notes situations where programs and
libraries differ.
maude_SOURCES
.o file (or
.lo when using libtool). Normally these object files are named
after the source file, but other factors can change this. If a file in
the _SOURCES variable has an unrecognized extension, Automake
will do one of two things with it. If a suffix rule exists for turning
files with the unrecognized extension into .o files, then
automake will treat this file as it will any other source file
(see Support for Other Languages). Otherwise, the file will be
ignored as though it were a header file.
The prefixes dist_ and nodist_ can be used to control
whether files listed in a _SOURCES variable are distributed.
dist_ is redundant, as sources are distributed by default, but it
can be specified for clarity if desired.
It is possible to have both dist_ and nodist_ variants of
a given _SOURCES variable at once; this lets you easily
distribute some files and not others, for instance:
nodist_maude_SOURCES = nodist.c
dist_maude_SOURCES = dist-me.c
By default the output file (on Unix systems, the .o file) will be
put into the current build directory. However, if the option
subdir-objects is in effect in the current directory then the
.o file will be put into the subdirectory named after the source
file. For instance, with subdir-objects enabled,
sub/dir/file.c will be compiled to sub/dir/file.o. Some
people prefer this mode of operation. You can specify
subdir-objects in AUTOMAKE_OPTIONS (see Options).
EXTRA_maude_SOURCES
Makefile.in
requires. 5 This means that, for example, you can't put a
configure substitution like @my_sources@ into a _SOURCES
variable. If you intend to conditionally compile source files and use
configure to substitute the appropriate object names into, e.g.,
_LDADD (see below), then you should list the corresponding source
files in the EXTRA_ variable.
This variable also supports dist_ and nodist_ prefixes,
e.g., nodist_EXTRA_maude_SOURCES.
maude_AR
$(AR) cru
followed by the name of the library and then the objects being put into
the library. You can override this by setting the _AR variable.
This is usually used with C++; some C++ compilers require a special
invocation in order to instantiate all the templates which should go
into a library. For instance, the SGI C++ compiler likes this variable set
like so:
libmaude_a_AR = $(CXX) -ar -o
maude_LIBADD
_LIBADD
variable. For instance this should be used for objects determined by
configure (see A Library).
maude_LDADD
_LDADD variable. For instance this should be used for objects
determined by configure (see Linking).
_LDADD and _LIBADD are inappropriate for passing
program-specific linker flags (except for -l, -L,
-dlopen and -dlpreopen). Use the _LDFLAGS variable
for this purpose.
For instance, if your configure.in uses AC_PATH_XTRA, you
could link your program against the X libraries like so:
maude_LDADD = $(X_PRE_LIBS) $(X_LIBS) $(X_EXTRA_LIBS)
maude_LDFLAGS
maude_DEPENDENCIES
_DEPENDENCIES variable. Each program depends on the
contents of such a variable, but no further interpretation is done.
If _DEPENDENCIES is not supplied, it is computed by Automake.
The automatically-assigned value is the contents of _LDADD or
_LIBADD, with most configure substitutions, -l, -L,
-dlopen and -dlpreopen options removed. The configure
substitutions that are left in are only $(LIBOBJS) and
$(ALLOCA); these are left because it is known that they will not
cause an invalid value for _DEPENDENCIES to be generated.
maude_LINK
_LINK variable must hold the name of a
command which can be passed all the .o file names as arguments.
Note that the name of the underlying program is not passed to
_LINK; typically one uses $@:
maude_LINK = $(CCLD) -magic -o $@
maude_CCASFLAGS
maude_CFLAGS
maude_CPPFLAGS
maude_CXXFLAGS
maude_FFLAGS
maude_GCJFLAGS
maude_LFLAGS
maude_OBJCFLAGS
maude_RFLAGS
maude_YFLAGS
_CCASFLAGS,
_CFLAGS,
_CPPFLAGS,
_CXXFLAGS,
_FFLAGS,
_GCJFLAGS,
_LFLAGS,
_OBJCFLAGS,
_RFLAGS, and
_YFLAGS.
When using a per-target compilation flag, Automake will choose a
different name for the intermediate object files. Ordinarily a file
like sample.c will be compiled to produce sample.o.
However, if the program's _CFLAGS variable is set, then the
object file will be named, for instance, maude-sample.o.
(See also renamed objects.)
In compilations with per-target flags, the ordinary AM_ form of
the flags variable is not automatically included in the
compilation (however, the user form of the variable is included).
So for instance, if you want the hypothetical maude compilations
to also use the value of AM_CFLAGS, you would need to write:
maude_CFLAGS = ... your flags ... $(AM_CFLAGS)
maude_DEPENDENCIES
_DEPENDENCIES variable. Each program depends on the
contents of such a variable, but no further interpretation is done.
If _DEPENDENCIES is not supplied, it is computed by Automake.
The automatically-assigned value is the contents of _LDADD or
_LIBADD, with most configure substitutions, -l, -L,
-dlopen and -dlpreopen options removed. The configure
substitutions that are left in are only @LIBOBJS@ and
@ALLOCA@; these are left because it is known that they will not
cause an invalid value for _DEPENDENCIES to be generated.
maude_SHORTNAME
maude_SHORTNAME to m, then in the above per-program
compilation flag example the object file would be named
m-sample.o rather than maude-sample.o. This facility is
rarely needed in practice, and we recommend avoiding it until you find
it is required.
Automake explicitly recognizes the use of $(LIBOBJS) and
$(ALLOCA), and uses this information, plus the list of
LIBOBJS files derived from configure.in to automatically
include the appropriate source files in the distribution (see Dist).
These source files are also automatically handled in the
dependency-tracking scheme; see See Dependencies.
$(LIBOBJS) and $(ALLOCA) are specially recognized in any
_LDADD or _LIBADD variable.
Occasionally it is useful to know which Makefile variables
Automake uses for compilations; for instance you might need to do your
own compilation in some special cases.
Some variables are inherited from Autoconf; these are CC,
CFLAGS, CPPFLAGS, DEFS, LDFLAGS, and
LIBS.
There are some additional variables which Automake itself defines:
AM_CPPFLAGS
-I and -D options should be listed here.
Automake already provides some -I options automatically. In
particular it generates -I$(srcdir), -I., and a -I
pointing to the directory holding config.h (if you've used
AC_CONFIG_HEADERS or AM_CONFIG_HEADER). You can disable
the default -I options using the nostdinc option.
AM_CPPFLAGS is ignored in preference to a per-executable (or
per-library) _CPPFLAGS variable if it is defined.
INCLUDES
AM_CPPFLAGS. It is an older name for
the same functionality. This variable is deprecated; we suggest using
AM_CPPFLAGS instead.
AM_CFLAGS
Makefile.am author can use to pass
in additional C compiler flags. It is more fully documented elsewhere.
In some situations, this is not used, in preference to the
per-executable (or per-library) _CFLAGS.
COMPILE
AM_LDFLAGS
Makefile.am author can use to pass
in additional linker flags. In some situations, this is not used, in
preference to the per-executable (or per-library) _LDFLAGS.
LINK
-o $@ and the usual variable references (for instance,
CFLAGS); it takes as "arguments" the names of the object files
and libraries to link in.
Automake has somewhat idiosyncratic support for Yacc and Lex.
Automake assumes that the .c file generated by yacc (or
lex) should be named using the basename of the input file. That
is, for a yacc source file foo.y, Automake will cause the
intermediate file to be named foo.c (as opposed to
y.tab.c, which is more traditional).
The extension of a yacc source file is used to determine the extension
of the resulting C or C++ file. Files with the extension
.y will be turned into .c files; likewise, .yy will
become .cc; .y++, c++; and .yxx,
.cxx.
Likewise, lex source files can be used to generate C or
C++; the extensions .l, .ll, .l++, and
.lxx are recognized.
You should never explicitly mention the intermediate (C or
C++) file in any SOURCES variable; only list the source
file.
The intermediate files generated by yacc (or lex) will be
included in any distribution that is made. That way the user doesn't
need to have yacc or lex.
If a yacc source file is seen, then your configure.in must
define the variable YACC. This is most easily done by invoking
the macro AC_PROG_YACC (see Particular Program Checks).
When yacc is invoked, it is passed YFLAGS and
AM_YFLAGS. The former is a user variable and the latter is
intended for the Makefile.am author.
AM_YFLAGS is usually used to pass the -d option to
yacc. Automake knows what this means and will automatically
adjust its rules to update and distribute the header file built by
yacc -d. What Automake cannot guess, though, is where this
header will be used: it is up to you to ensure the header gets built
before it is first used. Typically this is necessary in order for
dependency tracking to work when the header is included by another
file. The common solution is listing the header file in
BUILT_SOURCES (see Sources) as follows.
BUILT_SOURCES = parser.h
AM_YFLAGS = -d
bin_PROGRAMS = foo
foo_SOURCES = ... parser.y ...
If a lex source file is seen, then your configure.in
must define the variable LEX. You can use AC_PROG_LEX
to do this (see Particular Program Checks), but using AM_PROG_LEX macro
(see Macros) is recommended.
When lex is invoked, it is passed LFLAGS and
AM_LFLAGS. The former is a user variable and the latter is
intended for the Makefile.am author.
Automake makes it possible to include multiple yacc (or
lex) source files in a single program. When there is more than
one distinct yacc (or lex) source file in a directory,
Automake uses a small program called ylwrap to run yacc
(or lex) in a subdirectory. This is necessary because yacc's
output filename is fixed, and a parallel make could conceivably invoke
more than one instance of yacc simultaneously. The ylwrap
program is distributed with Automake. It should appear in the directory
specified by AC_CONFIG_AUX_DIR (see Finding `configure' Input), or the current
directory if that macro is not used in configure.in.
For yacc, simply managing locking is insufficient. The output of
yacc always uses the same symbol names internally, so it isn't
possible to link two yacc parsers into the same executable.
We recommend using the following renaming hack used in gdb:
#define yymaxdepth c_maxdepth
#define yyparse c_parse
#define yylex c_lex
#define yyerror c_error
#define yylval c_lval
#define yychar c_char
#define yydebug c_debug
#define yypact c_pact
#define yyr1 c_r1
#define yyr2 c_r2
#define yydef c_def
#define yychk c_chk
#define yypgo c_pgo
#define yyact c_act
#define yyexca c_exca
#define yyerrflag c_errflag
#define yynerrs c_nerrs
#define yyps c_ps
#define yypv c_pv
#define yys c_s
#define yy_yys c_yys
#define yystate c_state
#define yytmp c_tmp
#define yyv c_v
#define yy_yyv c_yyv
#define yyval c_val
#define yylloc c_lloc
#define yyreds c_reds
#define yytoks c_toks
#define yylhs c_yylhs
#define yylen c_yylen
#define yydefred c_yydefred
#define yydgoto c_yydgoto
#define yysindex c_yysindex
#define yyrindex c_yyrindex
#define yygindex c_yygindex
#define yytable c_yytable
#define yycheck c_yycheck
#define yyname c_yyname
#define yyrule c_yyrule
For each define, replace the c_ prefix with whatever you like.
These defines work for bison, byacc, and traditional
yaccs. If you find a parser generator that uses a symbol not
covered here, please report the new name so it can be added to the list.
Automake includes full support for C++.
Any package including C++ code must define the output variable
CXX in configure.in; the simplest way to do this is to use
the AC_PROG_CXX macro (see Particular Program Checks).
A few additional variables are defined when a C++ source file is seen:
CXX
CXXFLAGS
AM_CXXFLAGS
CXXFLAGS.
CXXCOMPILE
CXXLINK