Edit
kc3-lang/automake/doc/automake.texi
Alexandre Duret-Lutz
- doc/automake.texi
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\input texinfo @c -*-texinfo-*- @c %**start of header @setfilename automake.info @settitle automake @setchapternewpage off @c %**end of header @include version.texi @copying This manual is for @acronym{GNU} Automake (version @value{VERSION}, @value{UPDATED}), a program which creates GNU standards-compliant Makefiles from template files. Copyright @copyright{} 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. @quotation Permission is granted to copy, distribute and/or modify this document under the terms of the @acronym{GNU} Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover texts being ``A @acronym{GNU} Manual,'' and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled ``@acronym{GNU} Free Documentation License.'' (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify this @acronym{GNU} Manual, like @acronym{GNU} software. Copies published by the Free Software Foundation raise funds for @acronym{GNU} development.'' @end quotation @end copying @dircategory Software development @direntry * automake: (automake). Making Makefile.in's. @end direntry @dircategory Individual utilities @direntry * aclocal: (automake)Invoking aclocal. Generating aclocal.m4. @end direntry @titlepage @title GNU Automake @subtitle For version @value{VERSION}, @value{UPDATED} @author David MacKenzie @author Tom Tromey @author Alexandre Duret-Lutz @page @vskip 0pt plus 1filll @insertcopying @end titlepage @c Define an index of configure output variables. @defcodeindex ov @c Define an index of configure variables. @defcodeindex cv @c Define an index of options. @defcodeindex op @c Define an index of targets. @defcodeindex tr @c Define an index of commands. @defcodeindex cm @c Put the macros and variables into their own index. @c @syncodeindex fn cp @syncodeindex ov vr @syncodeindex cv vr @syncodeindex fn vr @c Put everything else into one index (arbitrarily chosen to be the concept index). @syncodeindex op cp @syncodeindex tr cp @syncodeindex cm cp @ifnottex @node Top @comment node-name, next, previous, up @top GNU Automake @insertcopying @menu * Introduction:: Automake's purpose * Generalities:: General ideas * Examples:: Some example packages * Invoking Automake:: Creating a Makefile.in * configure:: Scanning configure.ac or configure.in * Directories:: Declaring subdirectories * Programs:: Building programs and libraries * Other objects:: Other derived objects * Other GNU Tools:: Other GNU Tools * Documentation:: Building documentation * Install:: What gets installed * Clean:: What gets cleaned * Dist:: What goes in a distribution * Tests:: Support for test suites * Rebuilding:: Automatic rebuilding of Makefile * Options:: Changing Automake's behavior * Miscellaneous:: Miscellaneous rules * Include:: Including extra files in an Automake template. * Conditionals:: Conditionals * Gnits:: The effect of @code{--gnu} and @code{--gnits} * Cygnus:: The effect of @code{--cygnus} * Not Enough:: When Automake is not Enough * Distributing:: Distributing the Makefile.in * API versioning:: About compatibility between Automake versions * Upgrading:: Upgrading to a Newer Automake Version * FAQ:: Frequently Asked Questions * Copying This Manual:: How to make copies of this manual * Indices:: Indices of variables, macros, and concepts @detailmenu --- The Detailed Node Listing --- General ideas * General Operation:: General operation of Automake * Strictness:: Standards conformance checking * Uniform:: The Uniform Naming Scheme * Canonicalization:: How derived variables are named * User Variables:: Variables reserved for the user * Auxiliary Programs:: Programs automake might require Some example packages * Complete:: A simple example, start to finish * Hello:: A classic program * true:: Building true and false Scanning @file{configure.ac} * Requirements:: Configuration requirements * Optional:: Other things Automake recognizes * Invoking aclocal:: Auto-generating aclocal.m4 * aclocal options:: aclocal command line arguments * Macro search path:: Modifying aclocal's search path * Macros:: Autoconf macros supplied with Automake * Extending aclocal:: Writing your own aclocal macros * Local Macros:: Organizing local macros * Future of aclocal:: aclocal's scheduled death Auto-generating aclocal.m4 * aclocal options:: Options supported by aclocal * Macro search path:: How aclocal finds .m4 files Autoconf macros supplied with Automake * Public macros:: Macros that you can use. * Private macros:: Macros that you should not use. Directories * Subdirectories:: Building subdirectories recursively * Conditional Subdirectories:: Conditionally not building directories * Alternative:: Subdirectories without recursion * Subpackages:: Nesting packages Building Programs and Libraries * A Program:: Building a program * A Library:: Building a library * A Shared Library:: Building a Libtool library * Program and Library Variables:: Variables controlling program and library builds * Default _SOURCES:: Default source files * LIBOBJS:: Special handling for LIBOBJS and ALLOCA * Program variables:: Variables used when building a program * Yacc and Lex:: Yacc and Lex support * C++ Support:: Compiling C++ sources * Assembly Support:: Compiling assembly sources * Fortran 77 Support:: Compiling Fortran 77 sources * Fortran 9x Support:: Compiling Fortran 9x sources * Java Support:: Compiling Java sources * Support for Other Languages:: Compiling other languages * ANSI:: Automatic de-ANSI-fication * Dependencies:: Automatic dependency tracking * EXEEXT:: Support for executable extensions Building a program * Program Sources:: Defining program sources * Linking:: Linking with libraries or extra objects * Conditional Sources:: Handling conditional sources * Conditional Programs:: Building program conditionally Building a Shared Library * Libtool Concept:: Introducing Libtool * Libtool Libraries:: Declaring Libtool Libraries * Conditional Libtool Libraries:: Building Libtool Libraries Conditionally * Conditional Libtool Sources:: Choosing Library Sources Conditionally * Libtool Convenience Libraries:: Building Convenience Libtool Libraries * Libtool Modules:: Building Libtool Modules * Libtool Flags:: Using _LIBADD and _LDFLAGS * LTLIBOBJ:: Using $(LTLIBOBJ) * Libtool Issues:: Common Issues Related to Libtool's Use Fortran 77 Support * Preprocessing Fortran 77:: Preprocessing Fortran 77 sources * Compiling Fortran 77 Files:: Compiling Fortran 77 sources * Mixing Fortran 77 With C and C++:: Mixing Fortran 77 With C and C++ Mixing Fortran 77 With C and C++ * How the Linker is Chosen:: Automatic linker selection Fortran 9x Support * Compiling Fortran 9x Files:: Compiling Fortran 9x sources Other Derived Objects * Scripts:: Executable scripts * Headers:: Header files * Data:: Architecture-independent data files * Sources:: Derived sources Built sources * Built sources example:: Several ways to handle built sources. Other GNU Tools * Emacs Lisp:: Emacs Lisp * gettext:: Gettext * Libtool:: Libtool * Java:: Java * Python:: Python Building documentation * Texinfo:: Texinfo * Man pages:: Man pages Miscellaneous Rules * Tags:: Interfacing to etags and mkid * Suffixes:: Handling new file extensions * Multilibs:: Support for multilibs. When Automake Isn't Enough * Extending:: Adding new rules or overriding existing ones. * Third-Party Makefiles:: Integrating Non-Automake @file{Makefile}s. Frequently Asked Questions about Automake * CVS:: CVS and generated files * maintainer-mode:: missing and AM_MAINTAINER_MODE * wildcards:: Why doesn't Automake support wildcards? * distcleancheck:: Files left in build directory after distclean * renamed objects:: Why are object files sometimes renamed? * Multiple Outputs:: Writing rules for tools with many output files Copying This Manual * GNU Free Documentation License:: License for copying this manual Indices * Macro and Variable Index:: Index of Autoconf macros and Automake variables * General Index:: General index @end detailmenu @end menu @end ifnottex @node Introduction @chapter Introduction Automake is a tool for automatically generating @file{Makefile.in}s from files called @file{Makefile.am}. Each @file{Makefile.am} is basically a series of @code{make} variable definitions@footnote{These variables are also called @dfn{make macros} in Make terminology, however in this manual we reserve the term @dfn{macro} for Autoconf's macros.}, with rules being thrown in occasionally. The generated @file{Makefile.in}s are compliant with the GNU Makefile standards. @cindex GNU Makefile standards The GNU Makefile Standards Document (@pxref{Makefile Conventions, , , standards, The GNU Coding Standards}) 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 @file{Makefile.in}. There should generally be one @file{Makefile.am} per directory of a project. @cindex Constraints of Automake @cindex Automake constraints Automake does constrain a project in certain ways; for instance it assumes that the project uses Autoconf (@pxref{Top, , Introduction, autoconf, The Autoconf Manual}), and enforces certain restrictions on the @file{configure.ac} contents@footnote{Older Autoconf versions used @file{configure.in}. Autoconf 2.50 and greater promotes @file{configure.ac} over @file{configure.in}. The rest of this documentation will refer to @file{configure.ac}, but Automake also supports @file{configure.in} for backward compatibility.}. @cindex Automake requirements @cindex Requirements, Automake Automake requires @code{perl} in order to generate the @file{Makefile.in}s. However, the distributions created by Automake are fully GNU standards-compliant, and do not require @code{perl} in order to be built. @cindex BUGS, reporting @cindex Reporting BUGS @cindex E-mail, bug reports Mail suggestions and bug reports for Automake to @email{bug-automake@@gnu.org}. @node Generalities @chapter General ideas The following sections cover a few basic ideas that will help you understand how Automake works. @menu * General Operation:: General operation of Automake * Strictness:: Standards conformance checking * Uniform:: The Uniform Naming Scheme * Canonicalization:: How derived variables are named * User Variables:: Variables reserved for the user * Auxiliary Programs:: Programs automake might require @end menu @node General Operation @section General Operation Automake works by reading a @file{Makefile.am} and generating a @file{Makefile.in}. Certain variables and rules defined in the @file{Makefile.am} instruct Automake to generate more specialized code; for instance, a @samp{bin_PROGRAMS} variable definition will cause rules for compiling and linking programs to be generated. @cindex Non-standard targets @cindex cvs-dist, non-standard example @trindex cvs-dist The variable definitions and rules in the @file{Makefile.am} are copied verbatim into the generated file. This allows you to add arbitrary code into the generated @file{Makefile.in}. For instance the Automake distribution includes a non-standard rule for the @code{cvs-dist} target, which the Automake maintainer uses to make distributions from his source control system. @cindex GNU make extensions Note that most GNU make extensions are not recognized by Automake. Using such extensions in a @file{Makefile.am} will lead to errors or confusing behavior. @cindex Append operator A special exception is that the GNU make append operator, @samp{+=}, is supported. This operator appends its right hand argument to the variable specified on the left. Automake will translate the operator into an ordinary @samp{=} operator; @samp{+=} will thus work with any make program. Automake tries to keep comments grouped with any adjoining rules or variable definitions. @cindex Make targets, overriding @cindex Make rules, overriding @cindex Overriding make rules @cindex Overriding make targets A rule defined in @file{Makefile.am} generally overrides any such rule of a similar name that would be automatically generated by @code{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. @cindex Variables, overriding @cindex Overriding make variables Similarly, a variable defined in @file{Makefile.am} or @code{AC_SUBST}'ed from @file{configure.ac} will override any definition of the variable that @code{automake} would ordinarily create. This feature is more often useful than the ability to override a rule. Be warned that many of the variables generated by @code{automake} are considered to be for internal use only, and their names might change in future releases. @cindex Recursive operation of Automake @cindex Automake, recursive operation @cindex Example of recursive operation When examining a variable definition, Automake will recursively examine variables referenced in the definition. For example, if Automake is looking at the content of @code{foo_SOURCES} in this snippet @example xs = a.c b.c foo_SOURCES = c.c $(xs) @end example it would use the files @file{a.c}, @file{b.c}, and @file{c.c} as the contents of @code{foo_SOURCES}. @cindex ## (special Automake comment) @cindex Special Automake comment @cindex Comment, special to Automake Automake also allows a form of comment which is @emph{not} copied into the output; all lines beginning with @samp{##} (leading spaces allowed) are completely ignored by Automake. It is customary to make the first line of @file{Makefile.am} read: @cindex Makefile.am, first line @cindex First line of Makefile.am @example ## Process this file with automake to produce Makefile.in @end example @c FIXME discuss putting a copyright into Makefile.am here? I would but @c I don't know quite what to say. @c FIXME document customary ordering of Makefile.am here! @node Strictness @section Strictness @cindex Non-GNU packages 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. @cindex Strictness, defined @cindex Strictness, foreign @cindex foreign strictness @cindex Strictness, gnu @cindex gnu strictness @cindex Strictness, gnits @cindex gnits strictness To this end, Automake supports three levels of @dfn{strictness}---the strictness indicating how stringently Automake should check standards conformance. The valid strictness levels are: @table @samp @item foreign Automake will check for only those things which are absolutely required for proper operations. For instance, whereas GNU standards dictate the existence of a @file{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. @item gnu Automake will check---as much as possible---for compliance to the GNU standards for packages. This is the default. @item gnits Automake will check for compliance to the as-yet-unwritten @dfn{Gnits standards}. These are based on the GNU standards, but are even more detailed. Unless you are a Gnits standards contributor, it is recommended that you avoid this option until such time as the Gnits standard is actually published (which may never happen). @end table For more information on the precise implications of the strictness level, see @ref{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 @ref{Cygnus}. @node Uniform @section The Uniform Naming Scheme @cindex Uniform naming scheme Automake variables generally follow a @dfn{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 @code{configure} time determination of what should be built. @cindex _PROGRAMS primary variable @cindex PROGRAMS primary variable @cindex Primary variable, PROGRAMS @cindex Primary variable, defined At @code{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 @dfn{primary}. For instance, the primary @code{PROGRAMS} holds a list of programs which are to be compiled and linked. @vindex PROGRAMS @cindex pkglibdir, defined @cindex pkgincludedir, defined @cindex pkgdatadir, defined @vindex pkglibdir @vindex pkgincludedir @vindex pkgdatadir 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 (@pxref{Directory Variables, , , standards, The GNU Coding Standards}). Automake extends this list with @code{pkglibdir}, @code{pkgincludedir}, and @code{pkgdatadir}; these are the same as the non-@samp{pkg} versions, but with @samp{$(PACKAGE)} appended. For instance, @code{pkglibdir} is defined as @code{$(libdir)/$(PACKAGE)}. @cvindex PACKAGE, directory @cindex EXTRA_, prepending For each primary, there is one additional variable named by prepending @samp{EXTRA_} to the primary name. This variable is used to list objects which may or may not be built, depending on what @code{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 @file{Makefile.in} that will work in all cases. @cindex EXTRA_PROGRAMS, defined @cindex Example, EXTRA_PROGRAMS @cindex cpio example For instance, @code{cpio} decides at configure time which programs are built. Some of the programs are installed in @code{bindir}, and some are installed in @code{sbindir}: @example EXTRA_PROGRAMS = mt rmt bin_PROGRAMS = cpio pax sbin_PROGRAMS = $(MORE_PROGRAMS) @end example Defining a primary without a prefix as a variable, e.g., @code{PROGRAMS}, is an error. Note that the common @samp{dir} suffix is left off when constructing the variable names; thus one writes @samp{bin_PROGRAMS} and not @samp{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. @cindex Extending list of installation directories @cindex Installation directories, extending list 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. @samp{zar}) is valid if a variable of the same name with @samp{dir} appended is defined (e.g. @code{zardir}). @cindex HTML installation, example For instance, installation of HTML files is part of Automake, you could use this to install raw HTML documentation: @example htmldir = $(prefix)/html html_DATA = automake.html @end example @cindex noinst primary prefix, definition The special prefix @samp{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 (@pxref{A Library}), or helper scripts. @cindex check primary prefix, definition The special prefix @samp{check} indicates that the objects in question should not be built until the @code{make check} command is run. Those objects are not installed either. The current primary names are @samp{PROGRAMS}, @samp{LIBRARIES}, @samp{LISP}, @samp{PYTHON}, @samp{JAVA}, @samp{SCRIPTS}, @samp{DATA}, @samp{HEADERS}, @samp{MANS}, and @samp{TEXINFOS}. @vindex PROGRAMS @vindex LIBRARIES @vindex LISP @vindex PYTHON @vindex JAVA @vindex SCRIPTS @vindex DATA @vindex HEADERS @vindex MANS @vindex TEXINFOS Some primaries also allow additional prefixes which control other aspects of @code{automake}'s behavior. The currently defined prefixes are @samp{dist_}, @samp{nodist_}, and @samp{nobase_}. These prefixes are explained later (@pxref{Program and Library Variables}). @node Canonicalization @section How derived variables are named @cindex canonicalizing Automake variables Sometimes a Makefile variable name is derived from some text the maintainer supplies. For instance, a program name listed in @samp{_PROGRAMS} is rewritten into the name of a @samp{_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 @code{sniff-glue}, the derived variable name would be @code{sniff_glue_SOURCES}, not @code{sniff-glue_SOURCES}. Similarly the sources for a library named @code{libmumble++.a} should be listed in the @code{libmumble___a_SOURCES} variable. The strudel is an addition, to make the use of Autoconf substitutions in variable names less obfuscating. @node User Variables @section Variables reserved for the user @cindex variables, reserved for the user @cindex user variables Some @code{Makefile} variables are reserved by the GNU Coding Standards for the use of the ``user'' -- the person building the package. For instance, @code{CFLAGS} is one such variable. Sometimes package developers are tempted to set user variables such as @code{CFLAGS} because it appears to make their job easier. 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 @code{CC}, where they would make no sense.) The shadow variable is named by prepending @samp{AM_} to the user variable's name. For instance, the shadow variable for @code{YFLAGS} is @code{AM_YFLAGS}. @node Auxiliary Programs @section Programs automake might require @cindex Programs, auxiliary @cindex Auxiliary programs Automake sometimes requires helper programs so that the generated @file{Makefile} can do its work properly. There are a fairly large number of them, and we list them here. @table @code @item ansi2knr.c @itemx ansi2knr.1 These two files are used by the automatic de-ANSI-fication support (@pxref{ANSI}). @item compile This is a wrapper for compilers which don't accept both @samp{-c} and @samp{-o} at the same time. It is only used when absolutely required. Such compilers are rare. @item config.guess @itemx config.sub These programs compute the canonical triplets for the given build, host, or target architecture. These programs are updated regularly to support new architectures and fix probes broken by changes in new kernel versions. You are encouraged to fetch the latest versions of these files from @url{ftp://ftp.gnu.org/gnu/config/} before making a release. @item depcomp This program understands how to run a compiler so that it will generate not only the desired output but also dependency information which is then used by the automatic dependency tracking feature. @item elisp-comp This program is used to byte-compile Emacs Lisp code. @item install-sh This is a replacement for the @code{install} program which works on platforms where @code{install} is unavailable or unusable. @item mdate-sh This script is used to generate a @file{version.texi} file. It examines a file and prints some date information about it. @item missing This wraps a number of programs which are typically only required by maintainers. If the program in question doesn't exist, @code{missing} prints an informative warning and attempts to fix things so that the build can continue. @item mkinstalldirs This script used to be a wrapper around @code{mkdir -p}, which is not portable. Now we use prefer to use @code{install-sh -d} when configure finds that @code{mkdir -p} does not work, this makes one less script to distribute. For backward compatibility @code{mkinstalldirs} is still used and distributed when @code{automake} finds it in a package. But it is no longer installed automatically, and it should be safe to remove it. @item py-compile This is used to byte-compile Python scripts. @item texinfo.tex Not a program, this file is required for @code{make dvi}, @code{make ps} and @code{make pdf} to work when Texinfo sources are in the package. @item ylwrap This program wraps @code{lex} and @code{yacc} and ensures that, for instance, multiple @code{yacc} instances can be invoked in a single directory in parallel. @end table @node Examples @chapter Some example packages @menu * Complete:: A simple example, start to finish * Hello:: A classic program * true:: Building true and false @end menu @node Complete @section A simple example, start to finish @cindex Complete example Let's suppose you just finished writing @code{zardoz}, a program to make your head float from vortex to vortex. You've been using Autoconf to provide a portability framework, but your @file{Makefile.in}s have been ad-hoc. You want to make them bulletproof, so you turn to Automake. @cindex AM_INIT_AUTOMAKE, example use The first step is to update your @file{configure.ac} to include the commands that @code{automake} needs. The way to do this is to add an @code{AM_INIT_AUTOMAKE} call just after @code{AC_INIT}: @example AC_INIT(zardoz, 1.0) AM_INIT_AUTOMAKE @dots{} @end example Since your program doesn't have any complicating factors (e.g., it doesn't use @code{gettext}, it doesn't want to build a shared library), you're done with this part. That was easy! @cindex aclocal program, introduction @cindex aclocal.m4, preexisting @cindex acinclude.m4, defined Now you must regenerate @file{configure}. But to do that, you'll need to tell @code{autoconf} how to find the new macro you've used. The easiest way to do this is to use the @code{aclocal} program to generate your @file{aclocal.m4} for you. But wait@dots{} maybe you already have an @file{aclocal.m4}, because you had to write some hairy macros for your program. The @code{aclocal} program lets you put your own macros into @file{acinclude.m4}, so simply rename and then run: @example mv aclocal.m4 acinclude.m4 aclocal autoconf @end example @cindex zardoz example Now it is time to write your @file{Makefile.am} for @code{zardoz}. Since @code{zardoz} is a user program, you want to install it where the rest of the user programs go: @code{bindir}. Additionally, @code{zardoz} has some Texinfo documentation. Your @file{configure.ac} script uses @code{AC_REPLACE_FUNCS}, so you need to link against @samp{$(LIBOBJS)}. So here's what you'd write: @example bin_PROGRAMS = zardoz zardoz_SOURCES = main.c head.c float.c vortex9.c gun.c zardoz_LDADD = $(LIBOBJS) info_TEXINFOS = zardoz.texi @end example Now you can run @code{automake --add-missing} to generate your @file{Makefile.in} and grab any auxiliary files you might need, and you're done! @node Hello @section A classic program @cindex Example, GNU Hello @cindex Hello example @cindex GNU Hello, example @uref{ftp://prep.ai.mit.edu/pub/gnu/hello-1.3.tar.gz, GNU hello} is renowned for its classic simplicity and versatility. This section shows how Automake could be used with the GNU Hello package. The examples below are from the latest beta version of GNU Hello, but with all of the maintainer-only code stripped out, as well as all copyright comments. 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. @cindex configure.ac, from GNU Hello @cindex GNU Hello, configure.ac @cindex Hello, configure.ac Here is the @file{configure.ac} from GNU Hello. @strong{Please note:} The calls to @code{AC_INIT} and @code{AM_INIT_AUTOMAKE} in this example use a deprecated syntax. For the current approach, see the description of @code{AM_INIT_AUTOMAKE} in @ref{Public macros}. @c FIXME: This definitely requires an update, e.g. to GNU Hello 2.1.1. @example 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]) @end example The @samp{AM_} macros are provided by Automake (or the Gettext library); the rest are standard Autoconf macros. The top-level @file{Makefile.am}: @example EXTRA_DIST = BUGS ChangeLog.O SUBDIRS = doc intl po src tests @end example As you can see, all the work here is really done in subdirectories. The @file{po} and @file{intl} directories are automatically generated using @code{gettextize}; they will not be discussed here. @cindex Texinfo file handling example @cindex Example, handling Texinfo files In @file{doc/Makefile.am} we see: @example info_TEXINFOS = hello.texi hello_TEXINFOS = gpl.texi @end example This is sufficient to build, install, and distribute the GNU Hello manual. @cindex Regression test example @cindex Example, regression test Here is @file{tests/Makefile.am}: @example TESTS = hello EXTRA_DIST = hello.in testdata @end example The script @file{hello} is generated by @code{configure}, and is the only test case. @code{make check} will run this test. @cindex INCLUDES, example usage Last we have @file{src/Makefile.am}, where all the real work is done: @c FIXME: As all the Hello World excerpts in this manual, this @c shows deprecated features (here: $(INCLUDES)). @example 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)\" @end example @node true @section Building true and false @cindex Example, false and true @cindex false Example @cindex true Example Here is another, trickier example. It shows how to generate two programs (@code{true} and @code{false}) from the same source file (@file{true.c}). The difficult part is that each compilation of @file{true.c} requires different @code{cpp} flags. @example 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 @end example Note that there is no @code{true_SOURCES} definition. Automake will implicitly assume that there is a source file named @file{true.c}, and define rules to compile @file{true.o} and link @file{true}. The @code{true.o: true.c} rule supplied by the above @file{Makefile.am}, will override the Automake generated rule to build @file{true.o}. @code{false_SOURCES} is defined to be empty---that way no implicit value is substituted. Because we have not listed the source of @file{false}, we have to tell Automake how to link the program. This is the purpose of the @code{false_LDADD} line. A @code{false_DEPENDENCIES} variable, holding the dependencies of the @file{false} target will be automatically generated by Automake from the content of @code{false_LDADD}. The above rules won't work if your compiler doesn't accept both @samp{-c} and @samp{-o}. The simplest fix for this is to introduce a bogus dependency (to avoid problems with a parallel @code{make}): @example 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 @end example Also, these explicit rules do not work if the de-ANSI-fication feature is used (@pxref{ANSI}). Supporting de-ANSI-fication requires a little more work: @example 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 @end example 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 @code{true} and @code{false} in real life, you would probably use per-program compilation flags, like so: @example bin_PROGRAMS = false true false_SOURCES = true.c false_CPPFLAGS = -DEXIT_CODE=1 true_SOURCES = true.c true_CPPFLAGS = -DEXIT_CODE=0 @end example In this case Automake will cause @file{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 @file{false-true.o} and @file{true-true.o}. (The name of the object files rarely matters.) @node Invoking Automake @chapter Creating a @file{Makefile.in} @cindex Multiple configure.ac files @cindex Invoking Automake @cindex Automake, invoking To create all the @file{Makefile.in}s for a package, run the @code{automake} program in the top level directory, with no arguments. @code{automake} will automatically find each appropriate @file{Makefile.am} (by scanning @file{configure.ac}; @pxref{configure}) and generate the corresponding @file{Makefile.in}. Note that @code{automake} has a rather simplistic view of what constitutes a package; it assumes that a package has only one @file{configure.ac}, at the top. If your package has multiple @file{configure.ac}s, then you must run @code{automake} in each directory holding a @file{configure.ac}. (Alternatively, you may rely on Autoconf's @code{autoreconf}, which is able to recurse your package tree and run @code{automake} where appropriate.) You can optionally give @code{automake} an argument; @file{.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 @file{Makefile.in}. Note that @code{automake} must always be run from the topmost directory of a project, even if being used to regenerate the @file{Makefile.in} in some subdirectory. This is necessary because @code{automake} must scan @file{configure.ac}, and because @code{automake} uses the knowledge that a @file{Makefile.in} is in a subdirectory to change its behavior in some cases. @vindex AUTOCONF Automake will run @code{autoconf} to scan @file{configure.ac} and its dependencies (@file{aclocal.m4}), therefore @code{autoconf} must be in your @code{PATH}. If there is an @code{AUTOCONF} variable in your environment it will be used instead of @code{autoconf}, this allows you to select a particular version of Autoconf. By the way, don't misunderstand this paragraph: Automake runs @code{autoconf} to @strong{scan} your @file{configure.ac}, this won't build @file{configure} and you still have to run @code{autoconf} yourself for this purpose. @cindex Automake options @cindex Options, Automake @cindex Strictness, command line @code{automake} accepts the following options: @cindex Extra files distributed with Automake @cindex Files distributed with Automake @cindex config.guess @table @samp @item -a @itemx --add-missing @opindex -a @opindex --add-missing Automake requires certain common files to exist in certain situations; for instance @file{config.guess} is required if @file{configure.ac} runs @code{AC_CANONICAL_HOST}. Automake is distributed with several of these files (@pxref{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 @code{--copy}. Many of the potentially-missing files are common scripts whose location may be specified via the @code{AC_CONFIG_AUX_DIR} macro. Therefore, @code{AC_CONFIG_AUX_DIR}'s setting affects whether a file is considered missing, and where the missing file is added (@pxref{Optional}). @item --libdir=@var{dir} @opindex --libdir Look for Automake data files in directory @var{dir} instead of in the installation directory. This is typically used for debugging. @item -c @opindex -c @itemx --copy @opindex --copy When used with @code{--add-missing}, causes installed files to be copied. The default is to make a symbolic link. @item --cygnus @opindex --cygnus Causes the generated @file{Makefile.in}s to follow Cygnus rules, instead of GNU or Gnits rules. For more information, see @ref{Cygnus}. @item -f @opindex -f @itemx --force-missing @opindex --force-missing When used with @code{--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 @code{--copy}, copying the new file). @item --foreign @opindex --foreign Set the global strictness to @samp{foreign}. For more information, see @ref{Strictness}. @item --gnits @opindex --gnits Set the global strictness to @samp{gnits}. For more information, see @ref{Gnits}. @item --gnu @opindex --gnu Set the global strictness to @samp{gnu}. For more information, see @ref{Gnits}. This is the default strictness. @item --help @opindex --help Print a summary of the command line options and exit. @item -i @itemx --ignore-deps @opindex -i This disables the dependency tracking feature in generated @file{Makefile}s; see @ref{Dependencies}. @item --include-deps @opindex --include-deps This enables the dependency tracking feature. This feature is enabled by default. This option is provided for historical reasons only and probably should not be used. @item --no-force @opindex --no-force Ordinarily @code{automake} creates all @file{Makefile.in}s mentioned in @file{configure.ac}. This option causes it to only update those @file{Makefile.in}s which are out of date with respect to one of their dependents. @item -o @var{dir} @itemx --output-dir=@var{dir} @opindex -o @opindex --output-dir Put the generated @file{Makefile.in} in the directory @var{dir}. Ordinarily each @file{Makefile.in} is created in the directory of the corresponding @file{Makefile.am}. This option is deprecated and will be removed in a future release. @item -v @itemx --verbose @opindex -v @opindex --verbose Cause Automake to print information about which files are being read or created. @item --version @opindex --version Print the version number of Automake and exit. @item -W CATEGORY @item --warnings=@var{category} @opindex -W @opindex --warnings Output warnings falling in @var{category}. @var{category} can be one of: @table @samp @item gnu warnings related to the GNU Coding Standards (@pxref{Top, , , standards, The GNU Coding Standards}). @item obsolete obsolete features or constructions @item override user redefinitions of Automake rules or variables @item portability portability issues (e.g., use of Make features which are known not portable) @item syntax weird syntax, unused variables, typos @item unsupported unsupported or incomplete features @item all all the warnings @item none turn off all the warnings @item error treat warnings as errors @end table A category can be turned off by prefixing its name with @samp{no-}. For instance @samp{-Wno-syntax} will hide the warnings about unused variables. The categories output by default are @samp{syntax} and @samp{unsupported}. Additionally, @samp{gnu} is enabled in @samp{--gnu} and @samp{--gnits} strictness. @samp{portability} warnings are currently disabled by default, but they will be enabled in @samp{--gnu} and @samp{--gnits} strictness in a future release. @vindex WARNINGS The environment variable @samp{WARNINGS} can contain a comma separated list of categories to enable. It will be taken into account before the command-line switches, this way @samp{-Wnone} will also ignore any warning category enabled by @samp{WARNINGS}. This variable is also used by other tools like @command{autoconf}; unknown categories are ignored for this reason. @end table @node configure @chapter Scanning @file{configure.ac} @cindex configure.ac, scanning @cindex Scanning configure.ac Automake scans the package's @file{configure.ac} to determine certain information about the package. Some @code{autoconf} macros are required and some variables must be defined in @file{configure.ac}. Automake will also use information from @file{configure.ac} to further tailor its output. Automake also supplies some Autoconf macros to make the maintenance easier. These macros can automatically be put into your @file{aclocal.m4} using the @code{aclocal} program. @menu * Requirements:: Configuration requirements * Optional:: Other things Automake recognizes * Invoking aclocal:: Auto-generating aclocal.m4 * aclocal options:: aclocal command line arguments * Macro search path:: Modifying aclocal's search path * Macros:: Autoconf macros supplied with Automake * Extending aclocal:: Writing your own aclocal macros * Local Macros:: Organizing local macros * Future of aclocal:: aclocal's scheduled death @end menu @node Requirements @section Configuration requirements @cindex Automake requirements @cindex Requirements of Automake The one real requirement of Automake is that your @file{configure.ac} call @code{AM_INIT_AUTOMAKE}. This macro does several things which are required for proper Automake operation (@pxref{Macros}). @cvindex AM_INIT_AUTOMAKE Here are the other macros which Automake requires but which are not run by @code{AM_INIT_AUTOMAKE}: @table @code @item AC_CONFIG_FILES @itemx AC_OUTPUT Automake uses these to determine which files to create (@pxref{Output, , Creating Output Files, autoconf, The Autoconf Manual}). A listed file is considered to be an Automake generated @file{Makefile} if there exists a file with the same name and the @file{.am} extension appended. Typically, @code{AC_CONFIG_FILES([foo/Makefile])} will cause Automake to generate @file{foo/Makefile.in} if @file{foo/Makefile.am} exists. When using @code{AC_CONFIG_FILES} with multiple input files, as in @code{AC_CONFIG_FILES([Makefile:top.in:Makefile.in:bot.in])}, Automake will generate the first @file{.in} input file for which a @file{.am} file exists. If no such file exists the output file is not considered to be Automake generated. Files created by @code{AC_CONFIG_FILES} are removed by @code{make distclean}. @cvindex AC_CONFIG_FILES @cvindex AC_OUTPUT @end table @node Optional @section Other things Automake recognizes @cindex Macros Automake recognizes @cindex Recognized macros by Automake Every time Automake is run it calls Autoconf to trace @file{configure.ac}. This way it can recognize the use of certain macros and tailor the generated @file{Makefile.in} appropriately. Currently recognized macros and their effects are: @table @code @item AC_CONFIG_HEADERS Automake will generate rules to rebuild these headers. Older versions of Automake required the use of @code{AM_CONFIG_HEADER} (@pxref{Macros}); this is no longer the case today. @cvindex AC_CONFIG_HEADERS @item AC_CONFIG_LINKS Automake will generate rules to remove @file{configure} generated links on @code{make distclean} and to distribute named source files as part of @code{make dist}. @cvindex AC_CONFIG_LINKS @item AC_CONFIG_AUX_DIR Automake will look for various helper scripts, such as @file{install-sh}, in the directory named in this macro invocation. @c This list is accurate relative to version 1.8 (The full list of scripts is: @file{config.guess}, @file{config.sub}, @file{depcomp}, @file{elisp-comp}, @file{compile}, @file{install-sh}, @file{ltmain.sh}, @file{mdate-sh}, @file{missing}, @file{mkinstalldirs}, @file{py-compile}, @file{texinfo.tex}, and @file{ylwrap}.) Not all scripts are always searched for; some scripts will only be sought if the generated @file{Makefile.in} requires them. @cvindex AC_CONFIG_AUX_DIR If @code{AC_CONFIG_AUX_DIR} is not given, the scripts are looked for in their @samp{standard} locations. For @file{mdate-sh}, @file{texinfo.tex}, and @file{ylwrap}, the standard location is the source directory corresponding to the current @file{Makefile.am}. For the rest, the standard location is the first one of @file{.}, @file{..}, or @file{../..} (relative to the top source directory) that provides any one of the helper scripts. @xref{Input, , Finding `configure' Input, autoconf, The Autoconf Manual}. Required files from @code{AC_CONFIG_AUX_DIR} are automatically distributed, even if there is no @file{Makefile.am} in this directory. @item AC_CANONICAL_HOST Automake will ensure that @file{config.guess} and @file{config.sub} exist. Also, the @file{Makefile} variables @samp{host_alias} and @samp{host_triplet} are introduced. See @ref{Canonicalizing, , Getting the Canonical System Type, autoconf, The Autoconf Manual}. @cvindex AC_CANONICAL_HOST @vindex host_alias @vindex host_triplet @item AC_CANONICAL_SYSTEM This is similar to @code{AC_CANONICAL_HOST}, but also defines the @file{Makefile} variables @samp{build_alias} and @samp{target_alias}. @xref{Canonicalizing, , Getting the Canonical System Type, autoconf, The Autoconf Manual}. @cvindex AC_CANONICAL_SYSTEM @vindex build_alias @vindex target_alias @item AC_LIBSOURCE @itemx AC_LIBSOURCES @itemx AC_LIBOBJ Automake will automatically distribute any file listed in @code{AC_LIBSOURCE} or @code{AC_LIBSOURCES}. Note that the @code{AC_LIBOBJ} macro calls @code{AC_LIBSOURCE}. So if an Autoconf macro is documented to call @code{AC_LIBOBJ([file])}, then @file{file.c} will be distributed automatically by Automake. This encompasses many macros like @code{AC_FUNC_ALLOCA}, @code{AC_FUNC_MEMCMP}, @code{AC_REPLACE_FUNCS}, and others. @cvindex AC_LIBOBJ @cvindex AC_LIBSOURCE @cvindex AC_LIBSOURCES By the way, direct assignments to @code{LIBOBJS} are no longer supported. You should always use @code{AC_LIBOBJ} for this purpose. @xref{AC_LIBOBJ vs LIBOBJS, , @code{AC_LIBOBJ} vs. @code{LIBOBJS}, autoconf, The Autoconf Manual}. @cvindex LIBOBJS @item AC_PROG_RANLIB This is required if any libraries are built in the package. @xref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}. @cvindex AC_PROG_RANLIB @item AC_PROG_CXX This is required if any C++ source is included. @xref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}. @cvindex AC_PROG_CXX @item AC_PROG_F77 This is required if any Fortran 77 source is included. This macro is distributed with Autoconf version 2.13 and later. @xref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}. @cvindex AC_PROG_F77 @item AC_F77_LIBRARY_LDFLAGS This is required for programs and shared libraries that are a mixture of languages that include Fortran 77 (@pxref{Mixing Fortran 77 With C and C++}). @xref{Macros, , Autoconf macros supplied with Automake}. @cvindex AC_F77_LIBRARY_LDFLAGS @item AC_PROG_FC This is required if any Fortran 90/95 source is included. This macro is distributed with Autoconf version 2.58 and later. @xref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}. @cvindex AC_PROG_FC @item AC_PROG_LIBTOOL Automake will turn on processing for @code{libtool} (@pxref{Top, , Introduction, libtool, The Libtool Manual}). @cvindex AC_PROG_LIBTOOL @item AC_PROG_YACC If a Yacc source file is seen, then you must either use this macro or define the variable @samp{YACC} in @file{configure.ac}. The former is preferred (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}). @cvindex AC_PROG_YACC @cvindex YACC @item AC_PROG_LEX If a Lex source file is seen, then this macro must be used. @xref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}. @cvindex AC_PROG_LEX @item AC_SUBST @cvindex AC_SUBST The first argument is automatically defined as a variable in each generated @file{Makefile.in}. @xref{Setting Output Variables, , Setting Output Variables, autoconf, The Autoconf Manual}. If the Autoconf manual says that a macro calls @code{AC_SUBST} for @var{var}, or defines the output variable @var{var} then @var{var} will be defined in each @file{Makefile.in} generated by Automake. E.g. @code{AC_PATH_XTRA} defines @code{X_CFLAGS} and @code{X_LIBS}, so you can use these variables in any @file{Makefile.am} if @code{AC_PATH_XTRA} is called. @item AM_C_PROTOTYPES This is required when using automatic de-ANSI-fication; see @ref{ANSI}. @cvindex AM_C_PROTOTYPES @item AM_GNU_GETTEXT This macro is required for packages which use GNU gettext (@pxref{gettext}). It is distributed with gettext. If Automake sees this macro it ensures that the package meets some of gettext's requirements. @cvindex AM_GNU_GETTEXT @item AM_MAINTAINER_MODE @opindex --enable-maintainer-mode This macro adds a @samp{--enable-maintainer-mode} option to @code{configure}. If this is used, @code{automake} will cause @samp{maintainer-only} rules to be turned off by default in the generated @file{Makefile.in}s. This macro defines the @samp{MAINTAINER_MODE} conditional, which you can use in your own @file{Makefile.am}. @cvindex AM_MAINTAINER_MODE @item m4_include @cvindex m4_include Files included by @file{configure.ac} using this macro will be detected by Automake and automatically distributed. They will also appear as dependencies in @file{Makefile} rules. @code{m4_include} is seldom used by @file{configure.ac} authors, but can appear in @file{aclocal.m4} when @command{aclocal} detects that some required macros come from files local to your package (as opposed to macros installed in a system-wide directory, see @ref{Invoking aclocal}). @end table @node Invoking aclocal @section Auto-generating aclocal.m4 @cindex Invoking aclocal @cindex aclocal, Invoking Automake includes a number of Autoconf macros which can be used in your package (@pxref{Macros}); some of them are actually required by Automake in certain situations. These macros must be defined in your @file{aclocal.m4}; otherwise they will not be seen by @command{autoconf}. The @command{aclocal} program will automatically generate @file{aclocal.m4} files based on the contents of @file{configure.ac}. This provides a convenient way to get Automake-provided macros, without having to search around. The @command{aclocal} mechanism allows other packages to supply their own macros (@pxref{Extending aclocal}). You can also use it to maintain your own set of custom macros (@pxref{Local Macros}). At startup, @command{aclocal} scans all the @file{.m4} files it can find, looking for macro definitions (@pxref{Macro search path}). Then it scans @file{configure.ac}. 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 @file{aclocal.m4}. @emph{Putting} the file that contains the macro definition into @file{aclocal.m4} is usually done by copying the entire text of this file, including unused macro definitions as well as both @samp{#} and @samp{dnl} comments. If you want to make a comment which will be completely ignored by @command{aclocal}, use @samp{##} as the comment leader. When a file selected by @command{aclocal} is located in a subdirectory specified as a relative search path with @command{aclocal}'s @code{-I} argument, @command{aclocal} assumes the file belongs to the package and uses @code{m4_include} instead of copying it into @file{aclocal.m4}. This makes the package smaller, eases dependency tracking, and cause the file to be distributed automatically. (@pxref{Local Macros} for an example.) Any macro which is found in a system-wide directory, or via an absolute search path will be copied. So use @code{-I `pwd`/reldir} instead of @code{-I reldir} whenever some relative directory need to be considered outside the package. The contents of @file{acinclude.m4}, if this file exists, are also automatically included in @file{aclocal.m4}. We recommend against using @file{acinclude.m4} in new packages (@pxref{Local Macros}). @vindex AUTOM4TE While computing @file{aclocal.m4}, @code{aclocal} runs @code{autom4te} (@pxref{Using autom4te, , Using @code{Autom4te}, autoconf, The Autoconf Manual}) in order to trace the macros which are really used, and omit from @file{aclocal.m4} all macros which are mentioned but otherwise unexpanded (this can happen when a macro is called conditionally). @code{autom4te} is expected to be in the @code{PATH}, just as @code{autoconf}. Its location can be overridden using the @code{AUTOM4TE} environment variable. @menu * aclocal options:: Options supported by aclocal * Macro search path:: How aclocal finds .m4 files @end menu @node aclocal options @section aclocal options @cindex aclocal, Options @cindex Options, aclocal @code{aclocal} accepts the following options: @table @code @item --acdir=@var{dir} @opindex --acdir Look for the macro files in @var{dir} instead of the installation directory. This is typically used for debugging. @item --help @opindex --help Print a summary of the command line options and exit. @item -I @var{dir} @opindex -I Add the directory @var{dir} to the list of directories searched for @file{.m4} files. @item --force @opindex --force Always overwrite the output file. The default is to overwrite the output file only when really needed, i.e., when its contents changes or if one of its dependencies is younger. @item --output=@var{file} @opindex --output Cause the output to be put into @var{file} instead of @file{aclocal.m4}. @item --print-ac-dir @opindex --print-ac-dir Prints the name of the directory which @code{aclocal} will search to find third-party @file{.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. @item --verbose @opindex --verbose Print the names of the files it examines. @item --version @opindex --version Print the version number of Automake and exit. @end table @node Macro search path @section Macro search path @cindex Macro search path @cindex aclocal search path By default, @command{aclocal} searches for @file{.m4} files in the following directories, in this order: @table @code @item @var{acdir-APIVERSION} This is where the @file{.m4} macros distributed with automake itself are stored. @var{APIVERSION} depends on the automake release used; for automake 1.6.x, @var{APIVERSION} = @code{1.6}. @item @var{acdir} This directory is intended for third party @file{.m4} files, and is configured when @command{automake} itself is built. This is @file{@@datadir@@/aclocal/}, which typically expands to @file{$@{prefix@}/share/aclocal/}. To find the compiled-in value of @var{acdir}, use the @code{--print-ac-dir} option (@pxref{aclocal options}). @end table As an example, suppose that automake-1.6.2 was configured with @code{--prefix=/usr/local}. Then, the search path would be: @enumerate @item @file{/usr/local/share/aclocal-1.6/} @item @file{/usr/local/share/aclocal/} @end enumerate As explained in (@pxref{aclocal options}), there are several options that can be used to change or extend this search path. @subsection Modifying the macro search path: @code{--acdir} The most obvious option to modify the search path is @code{--acdir=@var{dir}}, which changes default directory and drops the @var{APIVERSION} directory. For example, if one specifies @code{--acdir=/opt/private/}, then the search path becomes: @enumerate @item @file{/opt/private/} @end enumerate Note that this option, @code{--acdir}, is intended for use by the internal automake test suite only; it is not ordinarily needed by end-users. @subsection Modifying the macro search path: @code{-I @var{dir}} Any extra directories specified using @code{-I} options (@pxref{aclocal options}) are @emph{prepended} to this search list. Thus, @code{aclocal -I /foo -I /bar} results in the following search path: @enumerate @item @file{/foo} @item @file{/bar} @item @var{acdir}-@var{APIVERSION} @item @var{acdir} @end enumerate @subsection Modifying the macro search path: @file{dirlist} @cindex @file{dirlist} There is a third mechanism for customizing the search path. If a @file{dirlist} file exists in @var{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 @emph{after} all other directories. For example, suppose @file{@var{acdir}/dirlist} contains the following: @example /test1 /test2 @end example @noindent and that @code{aclocal} was called with the @code{-I /foo -I /bar} options. Then, the search path would be @enumerate @item @file{/foo} @item @file{/bar} @item @var{acdir}-@var{APIVERSION} @item @var{acdir} @item @file{/test1} @item @file{/test2} @end enumerate If the @code{--acdir=@var{dir}} option is used, then @command{aclocal} will search for the @file{dirlist} file in @var{dir}. In the @code{--acdir=/opt/private/} example above, @command{aclocal} would look for @file{/opt/private/dirlist}. Again, however, the @code{--acdir} option is intended for use by the internal automake test suite only; @code{--acdir} is not ordinarily needed by end-users. @file{dirlist} is useful in the following situation: suppose that @code{automake} version @code{1.6.2} is installed with $prefix=/usr by the system vendor. Thus, the default search directories are @enumerate @item @file{/usr/share/aclocal-1.6/} @item @file{/usr/share/aclocal/} @end enumerate However, suppose further that many packages have been manually installed on the system, with $prefix=/usr/local, as is typical. In that case, many of these ``extra'' @file{.m4} files are in @file{/usr/local/share/aclocal}. The only way to force @file{/usr/bin/aclocal} to find these ``extra'' @file{.m4} files is to always call @code{aclocal -I /usr/local/share/aclocal}. This is inconvenient. With @file{dirlist}, one may create the file @file{/usr/share/aclocal/dirlist} @noindent which contains only the single line @file{/usr/local/share/aclocal} Now, the ``default'' search path on the affected system is @enumerate @item @file{/usr/share/aclocal-1.6/} @item @file{/usr/share/aclocal/} @item @file{/usr/local/share/aclocal/} @end enumerate without the need for @code{-I} options; @code{-I} options can be reserved for project-specific needs (@file{my-source-dir/m4/}), rather than using it to work around local system-dependent tool installation directories. Similarly, @file{dirlist} can be handy if you have installed a local copy Automake on your account and want @command{aclocal} to look for macros installed at other places on the system. @node Macros @section Autoconf macros supplied with Automake Automake ships with several Autoconf macros that you can use from your @file{configure.ac}. When you use one of them it will be included by @code{aclocal} in @file{aclocal.m4}. @menu * Public macros:: Macros that you can use. * Private macros:: Macros that you should not use. @end menu @c consider generating the following subsections automatically from m4 files. @node Public macros @subsection Public macros @table @code @item AM_CONFIG_HEADER Automake will generate rules to automatically regenerate the config header. This obsolete macro is a synonym of @code{AC_CONFIG_HEADERS} today (@pxref{Optional}). @cvindex AM_CONFIG_HEADER @item AM_ENABLE_MULTILIB This is used when a ``multilib'' library is being built. The first optional argument is the name of the @file{Makefile} being generated; it defaults to @samp{Makefile}. The second option argument is used to find the top source directory; it defaults to the empty string (generally this should not be used unless you are familiar with the internals). @xref{Multilibs}. @item AM_C_PROTOTYPES Check to see if function prototypes are understood by the compiler. If so, define @samp{PROTOTYPES} and set the output variables @samp{U} and @samp{ANSI2KNR} to the empty string. Otherwise, set @samp{U} to @samp{_} and @samp{ANSI2KNR} to @samp{./ansi2knr}. Automake uses these values to implement automatic de-ANSI-fication. @cvindex AM_C_PROTOTYPES @item AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL If the use of @code{TIOCGWINSZ} requires @file{<sys/ioctl.h>}, then define @code{GWINSZ_IN_SYS_IOCTL}. Otherwise @code{TIOCGWINSZ} can be found in @file{<termios.h>}. @cvindex AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL @item AM_INIT_AUTOMAKE([OPTIONS]) @itemx AM_INIT_AUTOMAKE(PACKAGE, VERSION, [NO-DEFINE]) Runs many macros required for proper operation of the generated Makefiles. This macro has two forms, the first of which is preferred. In this form, @code{AM_INIT_AUTOMAKE} is called with a single argument --- a space-separated list of Automake options which should be applied to every @file{Makefile.am} in the tree. The effect is as if each option were listed in @code{AUTOMAKE_OPTIONS}. The second, deprecated, form of @code{AM_INIT_AUTOMAKE} has two required arguments: the package and the version number. This form is obsolete because the @var{package} and @var{version} can be obtained from Autoconf's @code{AC_INIT} macro (which itself has an old and a new form). If your @file{configure.ac} has: @example AC_INIT(src/foo.c) AM_INIT_AUTOMAKE(mumble, 1.5) @end example you can modernize it as follows: @example AC_INIT(mumble, 1.5) AC_CONFIG_SRCDIR(src/foo.c) AM_INIT_AUTOMAKE @end example Note that if you're upgrading your @file{configure.ac} from an earlier version of Automake, it is not always correct to simply move the package and version arguments from @code{AM_INIT_AUTOMAKE} directly to @code{AC_INIT}, as in the example above. The first argument to @code{AC_INIT} should be the name of your package (e.g. @samp{GNU Automake}), not the tarball name (e.g. @samp{automake}) that you used to pass to @code{AM_INIT_AUTOMAKE}. Autoconf tries to derive a tarball name from the package name, which should work for most but not all package names. (If it doesn't work for yours, you can use the four-argument form of @code{AC_INIT} --- supported in Autoconf versions greater than 2.52g --- to provide the tarball name explicitly). By default this macro @code{AC_DEFINE}'s @samp{PACKAGE} and @samp{VERSION}. This can be avoided by passing the @samp{no-define} option, as in: @example AM_INIT_AUTOMAKE([gnits 1.5 no-define dist-bzip2]) @end example or by passing a third non-empty argument to the obsolete form. @cvindex PACKAGE, prevent definition @cvindex VERSION, prevent definition @item AM_PATH_LISPDIR Searches for the program @code{emacs}, and, if found, sets the output variable @code{lispdir} to the full path to Emacs' site-lisp directory. Note that this test assumes the @code{emacs} found to be a version that supports Emacs Lisp (such as @sc{gnu} Emacs or XEmacs). Other emacsen can cause this test to hang (some, like old versions of MicroEmacs, start up in interactive mode, requiring @samp{C-x C-c} to exit, which is hardly obvious for a non-emacs user). In most cases, however, you should be able to use @samp{C-c} to kill the test. In order to avoid problems, you can set @code{EMACS} to ``no'' in the environment, or use the @samp{--with-lispdir} option to @command{configure} to explicitly set the correct path (if you're sure you have an @code{emacs} that supports Emacs Lisp. @cvindex AM_PATH_LISPDIR @item AM_PROG_AS Use this macro when you have assembly code in your project. This will choose the assembler for you (by default the C compiler) and set @code{CCAS}, and will also set @code{CCASFLAGS} if required. @item AM_PROG_CC_C_O This is like @code{AC_PROG_CC_C_O}, but it generates its results in the manner required by automake. You must use this instead of @code{AC_PROG_CC_C_O} when you need this functionality. @item AM_PROG_LEX @cindex HP-UX 10, lex problems @cindex lex problems with HP-UX 10 Like @code{AC_PROG_LEX} (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}), but uses the @code{missing} script on systems that do not have @code{lex}. @samp{HP-UX 10} is one such system. @item AM_PROG_GCJ This macro finds the @code{gcj} program or causes an error. It sets @samp{GCJ} and @samp{GCJFLAGS}. @code{gcj} is the Java front-end to the GNU Compiler Collection. @cvindex AM_PROG_GCJ @item AM_SYS_POSIX_TERMIOS @cvindex am_cv_sys_posix_termios @cindex POSIX termios headers @cindex termios POSIX headers Check to see if POSIX termios headers and functions are available on the system. If so, set the shell variable @code{am_cv_sys_posix_termios} to @samp{yes}. If not, set the variable to @samp{no}. @item AM_WITH_DMALLOC @cvindex WITH_DMALLOC @cindex dmalloc, support for @opindex --with-dmalloc Add support for the @uref{ftp://ftp.letters.com/src/dmalloc/dmalloc.tar.gz, dmalloc} package. If the user configures with @samp{--with-dmalloc}, then define @code{WITH_DMALLOC} and add @samp{-ldmalloc} to @code{LIBS}. @item AM_WITH_REGEX @cvindex WITH_REGEX @opindex --with-regex @cindex regex package @cindex rx package Adds @samp{--with-regex} to the @code{configure} command line. If specified (the default), then the @samp{regex} regular expression library is used, @file{regex.o} is put into @samp{LIBOBJS}, and @samp{WITH_REGEX} is defined. If @samp{--without-regex} is given, then the @samp{rx} regular expression library is used, and @file{rx.o} is put into @samp{LIBOBJS}. @end table @node Private macros @subsection Private macros 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! @table @code @item _AM_DEPENDENCIES @itemx AM_SET_DEPDIR @itemx AM_DEP_TRACK @itemx AM_OUTPUT_DEPENDENCY_COMMANDS These macros are used to implement Automake's automatic dependency tracking scheme. They are called automatically by automake when required, and there should be no need to invoke them manually. @item AM_MAKE_INCLUDE This macro is used to discover how the user's @code{make} handles @code{include} statements. This macro is automatically invoked when needed; there should be no need to invoke it manually. @item AM_PROG_INSTALL_STRIP This is used to find a version of @code{install} which can be used to @code{strip} a program at installation time. This macro is automatically included when required. @item AM_SANITY_CHECK This checks to make sure that a file created in the build directory is newer than a file in the source directory. This can fail on systems where the clock is set incorrectly. This macro is automatically run from @code{AM_INIT_AUTOMAKE}. @end table @node Extending aclocal @section Writing your own aclocal macros @cindex aclocal, extending @cindex Extending aclocal The @command{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 macros for use by other programs. For instance the @command{gettext} library supplies a macro @code{AM_GNU_GETTEXT} which should be used by any package using @command{gettext}. When the library is installed, it installs this macro so that @command{aclocal} will find it. A macro file's name should end in @file{.m4}. Such files should be installed in @file{$(datadir)/aclocal}. This is as simple as writing: @example aclocaldir = $(datadir)/aclocal aclocal_DATA = mymacro.m4 myothermacro.m4 @end example A file of macros should be a series of properly quoted @code{AC_DEFUN}'s (@pxref{Macro Definitions, , , autoconf, The Autoconf Manual}). The @command{aclocal} programs also understands @code{AC_REQUIRE} (@pxref{Prerequisite Macros, , , autoconf, The Autoconf Manual}), so it is safe to put each macro in a separate file. Each file should have no side effects but macro definitions. Especially, any call to @code{AC_PREREQ} should be done inside the defined macro, not at the beginning of the file. @cindex underquoted AC_DEFUN @cvindex AC_DEFUN @cvindex AC_PREREQ Starting with Automake 1.8, @command{aclocal} will warn about all underquoted calls to @code{AC_DEFUN}. We realize this will annoy a lot of people, because @command{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 @command{aclocal} (@pxref{Future of aclocal}) will have to temporary include all these third party @file{.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 @example # bad style AC_PREREQ(2.57) AC_DEFUN(AX_FOOBAR, [AC_REQUIRE([AX_SOMETHING])dnl AX_FOO AX_BAR ]) @end example @noindent should be rewritten as @example AC_DEFUN([AX_FOOBAR], [AC_PREREQ(2.57)dnl AC_REQUIRE([AX_SOMETHING])dnl AX_FOO AX_BAR ]) @end example Wrapping the @code{AC_PREREQ} call inside the macro ensures that Autoconf 2.57 will not be required if @code{AX_FOOBAR} is not actually used. Most importantly, quoting the first argument of @code{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 @command{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. Another situation where @command{aclocal} is commonly used is to manage macros which are used locally by the package, @ref{Local Macros}. @node Local Macros @section Handling Local Macros Feature tests offered by Autoconf do not cover all needs. People often have to supplement existing tests with their own macros, or with third-party macros. There are two ways to organize custom macros in a package. The first possibility (the historical practice) is to list all your macros in @file{acinclude.m4}. This file will be included in @file{aclocal.m4} when you run @command{aclocal}, and its macro(s) will henceforth be visible to @command{autoconf}. However if it contains numerous macros, it will rapidly become difficult to maintain, and it will be almost impossible to share macros between packages. @vindex ACLOCAL_AMFLAGS The second possibility, which we do recommend, is to write each macro in its own file and gather all these files in a directory. This directory is usually called @file{m4/}. To build @file{aclocal.m4}, one should therefore instruct @command{aclocal} to scan @file{m4/}. From the command line, this is done with @code{aclocal -I m4}. The top-level @file{Makefile.am} should also be updated to define @example ACLOCAL_AMFLAGS = -I m4 @end example @code{ACLOCAL_AMFLAGS} contains options to pass to @command{aclocal} when @file{aclocal.m4} is to be rebuilt by @code{make}. This line is also used by @command{autoreconf} (@pxref{autoreconf Invocation, , Using @command{autoreconf} to Update @file{configure} Scripts, autoconf, The Autoconf Manual}) to run @command{aclocal} with suitable options, or by @command{autopoint} (@pxref{autopoint Invocation, , Invoking the @command{autopoint} Program, gettext, GNU gettext tools}) and @command{gettextize} (@pxref{gettextize Invocation, , Invoking the @command{gettextize} Program, gettext, GNU gettext tools}) to locate the place where Gettext's macros should be installed. So even if you do not really care about the rebuild rules, you should define @code{ACLOCAL_AMFLAGS}. When @code{aclocal -I m4} is run, it will build a @code{aclocal.m4} that @code{m4_include}s any file from @file{m4/} that defines a required macro. Macros not found locally will still be searched in system-wide directories, as explained in @ref{Macro search path}. Custom macros should be distributed for the same reason that @file{configure.ac} is: so that other people have all the sources of your package if they want to work on it. Actually, this distribution happens automatically because all @code{m4_include}d files are distributed. However there is no consensus on the distribution of third-party macros that your package may use. Many libraries install their own macro in the system-wide @command{aclocal} directory (@pxref{Extending aclocal}). For instance Guile ships with a file called @file{guile.m4} that contains the macro @code{GUILE_FLAGS} which can be used to define setup compiler and linker flags appropriate for using Guile. Using @code{GUILE_FLAGS} in @file{configure.ac} will cause @command{aclocal} to copy @file{guile.m4} into @file{aclocal.m4}, but as @file{guile.m4} is not part of the project, it will not be distributed. Technically, that means a user which needs to rebuild @file{aclocal.m4} will have to install Guile first. This is probably OK, if Guile already is a requirement to build the package. However, if Guile is only an optional feature, or if your package might run on architectures where Guile cannot be installed, this requirement will hinder development. An easy solution is to copy such third-party macros in your local @file{m4/} directory so they get distributed. @node Future of aclocal @section The Future of @command{aclocal} @cindex aclocal's scheduled death @command{aclocal} is expected to disappear. This feature really should not be offered by Automake. Automake should focus on generating @file{Makefile}s; dealing with M4 macros really is Autoconf's job. That some people install Automake just to use @command{aclocal}, but do not use @command{automake} otherwise is an indication of how that feature is misplaced. The new implementation will probably be done slightly differently. For instance it could enforce the @file{m4/}-style layout discussed in @ref{Local Macros}, and take care of copying (and even updating) third-party macros from @file{/usr/share/aclocal/} into the local @file{m4/} directory. We have no idea when and how this will happen. This has been discussed several times in the past, but someone still has to commit itself to that non-trivial task. From the user point of view, @command{aclocal}'s removal might turn out to be painful. There is a simple precaution that you may take to make that switch more seamless: never call @command{aclocal} yourself. Keep this guy under the exclusive control of @command{autoreconf} and Automake's rebuild rules. Hopefully you won't need to worry about things breaking, when @command{aclocal} disappears, because everything will have been taken care of. If otherwise you used to call @command{aclocal} directly yourself or from some script, you will quickly notice the change. Many packages come with a script called @file{bootstrap.sh} or @file{autogen.sh}, that will just call @command{aclocal}, @command{libtoolize}, @command{gettextize} or @command{autopoint}, @command{autoconf}, @command{autoheader}, and @command{automake} in the right order. Actually this is precisely what @command{autoreconf} can do for you. If your package has such a @file{bootstrap.sh} or @file{autogen.sh} script, consider using @command{autoreconf}. That should simplify its logic a lot (less things to maintain, yum!), it's even likely you will not need the script anymore, and more to the point you will not call @command{aclocal} directly anymore. For the time being, third-party packages should continue to install public macros into @code{/usr/share/aclocal/}. If @command{aclocal} is replaced by another tool it might make sense to rename the directory, but supporting @code{/usr/share/aclocal/} for backward compatibility should be really easy provided all macros are properly written (@pxref{Extending aclocal}). @node Directories @chapter Directories For simple projects that distributes all files in the same directory it is enough to have a single @file{Makefile.am} that builds everything in place. In larger projects it is common to organize files in different directories, in a tree. For instance one directory per program, per library or per module. The traditional approach is to build these subdirectory recursively: each directory contains its @file{Makefile} (generated from @file{Makefile.am}), and when @command{make} is run from the top level directory it enters each subdirectory in turn to build its contents. @menu * Subdirectories:: Building subdirectories recursively * Conditional Subdirectories:: Conditionally not building directories * Alternative:: Subdirectories without recursion * Subpackages:: Nesting packages @end menu @node Subdirectories @section Recursing subdirectories @cindex SUBDIRS, explained In packages with subdirectories, the top level @file{Makefile.am} must tell Automake which subdirectories are to be built. This is done via the @code{SUBDIRS} variable. @vindex SUBDIRS The @code{SUBDIRS} variable holds a list of subdirectories in which building of various sorts can occur. The rules for many targets (e.g. @code{all}) in the generated @file{Makefile} will run commands both locally and in all specified subdirectories. Note that the directories listed in @code{SUBDIRS} are not required to contain @file{Makefile.am}s; only @file{Makefile}s (after configuration). This allows inclusion of libraries from packages which do not use Automake (such as @code{gettext}; see also @ref{Third-Party Makefiles}). In packages that use subdirectories, the top-level @file{Makefile.am} is often very short. For instance, here is the @file{Makefile.am} from the GNU Hello distribution: @example EXTRA_DIST = BUGS ChangeLog.O README-alpha SUBDIRS = doc intl po src tests @end example When Automake invokes @code{make} in a subdirectory, it uses the value of the @code{MAKE} variable. It passes the value of the variable @code{AM_MAKEFLAGS} to the @code{make} invocation; this can be set in @file{Makefile.am} if there are flags you must always pass to @code{make}. @vindex MAKE @vindex AM_MAKEFLAGS The directories mentioned in @code{SUBDIRS} are usually direct children of the current directory, each subdirectory containing its own @file{Makefile.am} with a @code{SUBDIRS} pointing to deeper subdirectories. Automake can be used to construct packages of arbitrary depth this way. By default, Automake generates @file{Makefiles} which work depth-first in postfix order: the subdirectories are built before the current directory. However, it is possible to change this ordering. You can do this by putting @samp{.} into @code{SUBDIRS}. For instance, putting @samp{.} first will cause a @samp{prefix} ordering of directories. Using @example SUBDIRS = lib src . test @end example @noindent will cause @file{lib/} to be built before @file{src/}, then the current directory will be built, finally the @file{test/} directory will be built. It is customary to arrange test directories to be built after everything else since they are meant to test what have been constructed. All @samp{clean} rules are run in reverse order of build rules. @node Conditional Subdirectories @section Conditional Subdirectories @cindex Subdirectories, building conditionally @cindex Conditional subdirectories @cindex @code{SUBDIRS}, conditional @cindex Conditional @code{SUBDIRS} It is possible to define the @code{SUBDIRS} variable conditionally if, like in the case of GNU @code{Inetutils}, you want to only build a subset of the entire package. To illustrate how this works, let's assume we have two directories @file{src/} and @file{opt/}. @file{src/} should always be built, but we want to decide in @code{./configure} whether @file{opt/} will be built or not. (For this example we will assume that @file{opt/} should be built when the variable @code{$want_opt} was set to @code{yes}.) Running @code{make} should thus recurse into @file{src/} always, and then maybe in @file{opt/}. However @code{make dist} should always recurse into both @file{src/} and @file{opt/}. Because @file{opt/} should be distributed even if it is not needed in the current configuration. This means @file{opt/Makefile} should be created @emph{unconditionally}. There are two ways to setup a project like this. You can use Automake conditionals (@pxref{Conditionals}) or use Autoconf @code{AC_SUBST} variables (@pxref{Setting Output Variables, , Setting Output Variables, autoconf, The Autoconf Manual}). Using Automake conditionals is the preferred solution. Before we illustrate these two possibility, let's introduce @code{DIST_SUBDIRS}. @subsection @code{SUBDIRS} vs. @code{DIST_SUBDIRS} @cindex @code{DIST_SUBDIRS}, explained Automake considers two sets of directories, defined by the variables @code{SUBDIRS} and @code{DIST_SUBDIRS}. @code{SUBDIRS} contains the subdirectories of the current directory that must be built (@pxref{Subdirectories}). It must be defined manually; Automake will never guess a directory is to be built. As we will see in the next two sections, it is possible to define it conditionally so that some directory will be omitted from the build. @code{DIST_SUBDIRS} is used in rules that need to recurse in all directories, even those which have been conditionally left out of the build. Recall our example where we may not want to build subdirectory @file{opt/}, but yet we want to distribute it? This is where @code{DIST_SUBDIRS} come into play: @code{opt} may not appear in @code{SUBDIRS}, but it must appear in @code{DIST_SUBDIRS}. Precisely, @code{DIST_SUBDIRS} is used by @code{make dist}, @code{make distclean}, and @code{make maintainer-clean}. All other recursive rules use @code{SUBDIRS}. If @code{SUBDIRS} is defined conditionally using Automake conditionals, Automake will define @code{DIST_SUBDIRS} automatically from the possibles values of @code{SUBDIRS} in all conditions. If @code{SUBDIRS} contains @code{AC_SUBST} variables, @code{DIST_SUBDIRS} will not be defined correctly because Automake does not know the possible values of these variables. In this case @code{DIST_SUBDIRS} needs to be defined manually. @subsection Conditional subdirectories with @code{AM_CONDITIONAL} @cindex @code{SUBDIRS} and @code{AM_CONDITIONAL} @cindex @code{AM_CONDITIONAL} and @code{SUBDIRS} @c The test case for the setup described here is @c test/subdircond2.test @c Try to keep it in sync. @file{configure} should output the @file{Makefile} for each directory and define a condition into which @file{opt/} should be built. @example @dots{} AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes]) AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile]) @dots{} @end example Then @code{SUBDIRS} can be defined in the top-level @file{Makefile.am} as follows. @example if COND_OPT MAYBE_OPT = opt endif SUBDIRS = src $(MAYBE_OPT) @end example As you can see, running @code{make} will rightly recurse into @file{src/} and maybe @file{opt/}. @vindex DIST_SUBDIRS As you can't see, running @code{make dist} will recurse into both @file{src/} and @file{opt/} directories because @code{make dist}, unlike @code{make all}, doesn't use the @code{SUBDIRS} variable. It uses the @code{DIST_SUBDIRS} variable. In this case Automake will define @code{DIST_SUBDIRS = src opt} automatically because it knows that @code{MAYBE_OPT} can contain @code{opt} in some condition. @subsection Conditional Subdirectories with @code{AC_SUBST} @cindex @code{SUBDIRS} and @code{AC_SUBST} @cindex @code{AC_SUBST} and @code{SUBDIRS} @c The test case for the setup described here is @c test/subdircond3.test @c Try to keep it in sync. Another possibility is to define @code{MAYBE_OPT} from @file{./configure} using @code{AC_SUBST}: @example @dots{} if test "$want_opt" = yes; then MAYBE_OPT=opt else MAYBE_OPT= fi AC_SUBST([MAYBE_OPT]) AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile]) @dots{} @end example In this case the top-level @file{Makefile.am} should look as follows. @example SUBDIRS = src $(MAYBE_OPT) DIST_SUBDIRS = src opt @end example The drawback is that since Automake cannot guess what the possible values of @code{MAYBE_OPT} are, it is necessary to define @code{DIST_SUBDIRS}. @subsection Non-configured Subdirectories The semantic of @code{DIST_SUBDIRS} is often misunderstood by some users that try to @emph{configure and build} subdirectories conditionally. Here by configuring we mean creating the @file{Makefile} (it might also involve running a nested @command{configure} script: this is a costly operation that explains why people want to do it conditionally, but only the @file{Makefile} is relevant to the discussion). The above examples all assume that every @file{Makefile} is created, even in directories that are not going to be built. The simple reason is that we want @code{make dist} to distribute even the directories that are not being built (e.g. platform-dependent code), hence @file{make dist} must recurse into the subdirectory, hence this directory must be configured and appear in @code{DIST_SUBDIRS}. Building packages that do not configure every subdirectory is a tricky business, and we do not recommend it to the novice as it is easy to produce an incomplete tarball by mistake. We will not discuss this topic in depth here, yet for the adventurous there are a few rules to remember. @cartouche @itemize @item @code{SUBDIRS} should always be a subset of @code{DIST_SUBDIRS}. It makes little sense to have a directory in @code{SUBDIRS} that is not in @code{DIST_SUBDIRS}. Think of the former as a way to tell which directories listed in the latter should be built. @item Any directory listed in @code{DIST_SUBDIRS} and @code{SUBDIRS} must be configured. I.e., the @file{Makefile} must exists or the recursive @code{make} rules will not be able to process the directory. @item Any configured directory must be listed in @code{DIST_SUBDIRS}. So that the cleaning rule remove the generated @file{Makefile}s. It would be correct to see @code{DIST_SUBDIRS} as a variable that lists all the directories that have been configured. @end itemize @end cartouche In order to prevent recursion in some non-configured directory you must therefore ensure that this directory do not appear in @code{DIST_SUBDIRS} (and @code{SUBDIRS}). For instance if you define @code{SUBDIRS} conditionally using @code{AC_SUBST} and do not define @code{DIST_SUBDIRS} explicitly, it will be default to @code{$(SUBDIRS)}; another possibility is to force @code{DIST_SUBDIRS = $(SUBDIRS)}. @node Alternative @section An Alternative Approach to Subdirectories If you've ever read Peter Miller's excellent paper, @uref{http://www.pcug.org.au/~millerp/rmch/recu-make-cons-harm.html, Recursive Make Considered Harmful}, the preceding sections on the use of subdirectories will probably come as unwelcome advice. For those who haven't read the paper, Miller's main thesis is that recursive @code{make} invocations are both slow and error-prone. Automake provides sufficient cross-directory support @footnote{We believe. This work is new and there are probably warts. @xref{Introduction}, for information on reporting bugs.} to enable you to write a single @file{Makefile.am} for a complex multi-directory package. By default an installable file specified in a subdirectory will have its directory name stripped before installation. For instance, in this example, the header file will be installed as @file{$(includedir)/stdio.h}: @example include_HEADERS = inc/stdio.h @end example @cindex nobase_ @cindex Path stripping, avoiding @cindex Avoiding path stripping However, the @samp{nobase_} prefix can be used to circumvent this path stripping. In this example, the header file will be installed as @file{$(includedir)/sys/types.h}: @example nobase_include_HEADERS = sys/types.h @end example @cindex nobase_ and dist_ or nodist_ @cindex dist_ and nobase_ @cindex nodist_ and nobase_ @samp{nobase_} should be specified first when used in conjunction with either @samp{dist_} or @samp{nodist_} (@pxref{Dist}). For instance: @example nobase_dist_pkgdata_DATA = images/vortex.pgm @end example @node Subpackages @section Nesting Packages @cindex Nesting packages @cindex Subpackages @cvindex AC_CONFIG_SUBDIRS @cvindex AC_CONFIG_AUX_DIR In the GNU Build System, packages can be nested to arbitrary depth. This means that a package can embedded other packages with their own @file{configure}, @file{Makefile}s, etc. These other packages should just appear as subdirectories of their parent package. They must be listed in @code{SUBDIRS} like other ordinary directories. However the subpackage's @file{Makefile}s should be output by its own @file{configure} script, not by the parent's @file{configure}. This is achieved using the @code{AC_CONFIG_SUBDIRS} Autoconf macro (@pxref{Subdirectories, AC_CONFIG_SUBDIRS, Configuring Other Packages in Subdirectories, autoconf, The Autoconf Manual}). Here is an example package for an @code{arm} program that links with an @code{hand} library that is a nested package in subdirectory @file{hand/}. @code{arm}'s @file{configure.ac}: @example AC_INIT([arm], [1.0]) AC_CONFIG_AUX_DIR([.]) AM_INIT_AUTOMAKE AC_PROG_CC AC_CONFIG_FILES([Makefile]) # Call hand's ./configure script recursively. AC_CONFIG_SUBDIRS([hand]) AC_OUTPUT @end example @code{arm}'s @file{Makefile.am}: @example # Build the library in the hand subdirectory first. SUBDIRS = hand # Include hand's header when compiling this directory. AM_CPPFLAGS = -I$(srcdir)/hand bin_PROGRAMS = arm arm_SOURCES = arm.c # link with the hand library. arm_LDADD = hand/libhand.a @end example Now here is @code{hand}'s @file{hand/configure.ac}: @example AC_INIT([hand], [1.2]) AC_CONFIG_AUX_DIR([.]) AM_INIT_AUTOMAKE AC_PROG_CC AC_PROG_RANLIB AC_CONFIG_FILES([Makefile]) AC_OUTPUT @end example @noindent and its @file{hand/Makefile.am}: @example lib_LIBRARIES = libhand.a libhand_a_SOURCES = hand.c @end example When @code{make dist} is run from the top-level directory it will create an archive @file{arm-1.0.tar.gz} that contains the @code{arm} code as well as the @file{hand} subdirectory. This package can be built and installed like any ordinary package, with the usual @code{./configure && make && make install} sequence (the @code{hand} subpackage will be built and installed by the process). When @code{make dist} is run from the hand directory, it will create a self-contained @file{hand-1.2.tar.gz} archive. So although it appears to be embedded in another package, it can still be used separately. The purpose of the @code{AC_CONFIG_AUX_DIR([.])} instruction is to force Automake and Autoconf into search auxiliary script in the current directory. For instance this means that there will be two copies of @file{install-sh}: one in the top-level of the @code{arm} package, and another one in the @file{hand/} subdirectory for the @code{hand} package. The historical default is to search these auxiliary scripts in the immediate parent and grand-parent directories. So if the @code{AC_CONFIG_AUX_DIR([.])} line was removed from @file{hand/configure.ac}, that subpackage would share the auxiliary script of the @code{arm} package. This may looks like a gain in size (a few kilobytes), but it is actually a loss of modularity as the @code{hand} subpackage is no longer self-contained (@code{make dist} in the subdirectory will not work anymore). Packages that do not use Automake need more work to be integrated this way. @xref{Third-Party Makefiles}. @node Programs @chapter Building Programs and Libraries A large part of Automake's functionality is dedicated to making it easy to build programs and libraries. @menu * A Program:: Building a program * A Library:: Building a library * A Shared Library:: Building a Libtool library * Program and Library Variables:: Variables controlling program and library builds * Default _SOURCES:: Default source files * LIBOBJS:: Special handling for LIBOBJS and ALLOCA * Program variables:: Variables used when building a program * Yacc and Lex:: Yacc and Lex support * C++ Support:: Compiling C++ sources * Assembly Support:: Compiling assembly sources * Fortran 77 Support:: Compiling Fortran 77 sources * Fortran 9x Support:: Compiling Fortran 9x sources * Java Support:: Compiling Java sources * Support for Other Languages:: Compiling other languages * ANSI:: Automatic de-ANSI-fication * Dependencies:: Automatic dependency tracking * EXEEXT:: Support for executable extensions @end menu @node A Program @section Building a program 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 (@pxref{A Library}) and libtool libraries (@pxref{A Shared Library}). @menu * Program Sources:: Defining program sources * Linking:: Linking with libraries or extra objects * Conditional Sources:: Handling conditional sources * Conditional Programs:: Building program conditionally @end menu @node Program Sources @subsection Defining program sources @cindex PROGRAMS, bindir @vindex bin_PROGRAMS @vindex sbin_PROGRAMS @vindex libexec_PROGRAMS @vindex pkglib_PROGRAMS @vindex noinst_PROGRAMS @vindex check_PROGRAMS In a directory containing source that gets built into a program (as opposed to a library or a script), the @samp{PROGRAMS} primary is used. Programs can be installed in @code{bindir}, @code{sbindir}, @code{libexecdir}, @code{pkglibdir}, or not at all (@samp{noinst}). They can also be built only for @code{make check}, in which case the prefix is @samp{check}. For instance: @example bin_PROGRAMS = hello @end example In this simple case, the resulting @file{Makefile.in} will contain code to generate a program named @code{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 @code{hello_SOURCES} is used to specify which source files get built into an executable: @example hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h @end example This causes each mentioned @samp{.c} file to be compiled into the corresponding @samp{.o}. Then all are linked to produce @file{hello}. @cindex _SOURCES primary, defined @cindex SOURCES primary, defined @cindex Primary variable, SOURCES If @samp{hello_SOURCES} is not specified, then it defaults to the single file @file{hello.c} (@pxref{Default _SOURCES}). @vindex _SOURCES @vindex SOURCES Multiple programs can be built in a single directory. Multiple programs can share a single source file, which must be listed in each @samp{_SOURCES} definition. @cindex Header files in _SOURCES @cindex _SOURCES and header files Header files listed in a @samp{_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 @file{configure} in a @samp{_SOURCES} variable; this file should not be distributed. Lex (@samp{.l}) and Yacc (@samp{.y}) files can also be listed; see @ref{Yacc and Lex}. @node Linking @subsection Linking the program If you need to link against libraries that are not found by @code{configure}, you can use @code{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 @code{AM_LDFLAGS} for this purpose. @vindex LDADD @vindex AM_LDFLAGS @cindex prog_LDADD, defined Sometimes, multiple programs are built in one directory but do not share the same link-time requirements. In this case, you can use the @samp{@var{prog}_LDADD} variable (where @var{prog} is the name of the program as it appears in some @samp{_PROGRAMS} variable, and usually written in lowercase) to override the global @code{LDADD}. If this variable exists for a given program, then that program is not linked using @code{LDADD}. @vindex _LDADD For instance, in GNU cpio, @code{pax}, @code{cpio} and @code{mt} are linked against the library @file{libcpio.a}. However, @code{rmt} is built in the same directory, and has no such link requirement. Also, @code{mt} and @code{rmt} are only built on certain architectures. Here is what cpio's @file{src/Makefile.am} looks like (abridged): @example bin_PROGRAMS = cpio pax $(MT) libexec_PROGRAMS = $(RMT) EXTRA_PROGRAMS = mt rmt LDADD = ../lib/libcpio.a $(INTLLIBS) rmt_LDADD = cpio_SOURCES = @dots{} pax_SOURCES = @dots{} mt_SOURCES = @dots{} rmt_SOURCES = @dots{} @end example @cindex _LDFLAGS, defined @samp{@var{prog}_LDADD} is inappropriate for passing program-specific linker flags (except for @samp{-l}, @samp{-L}, @samp{-dlopen} and @samp{-dlpreopen}). So, use the @samp{@var{prog}_LDFLAGS} variable for this purpose. @vindex _LDFLAGS @cindex _DEPENDENCIES, defined It is also occasionally useful to have a program depend on some other target which is not actually part of that program. This can be done using the @samp{@var{prog}_DEPENDENCIES} variable. Each program depends on the contents of such a variable, but no further interpretation is done. If @samp{@var{prog}_DEPENDENCIES} is not supplied, it is computed by Automake. The automatically-assigned value is the contents of @samp{@var{prog}_LDADD}, with most configure substitutions, @samp{-l}, @samp{-L}, @samp{-dlopen} and @samp{-dlpreopen} options removed. The configure substitutions that are left in are only @samp{$(LIBOBJS)} and @samp{$(ALLOCA)}; these are left because it is known that they will not cause an invalid value for @samp{@var{prog}_DEPENDENCIES} to be generated. @node Conditional Sources @subsection Conditional compilation of sources You can't put a configure substitution (e.g., @samp{@@FOO@@} or @samp{$(FOO)} where @code{FOO} is defined via @code{AC_SUBST}) into a @samp{_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 @code{_LDADD} variables, the other is to use an Automake conditional. @subsubsection Conditional compilation using @code{_LDADD} substitutions @cindex EXTRA_prog_SOURCES, defined 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 @samp{EXTRA_} variable. For instance, if @file{hello-linux.c} or @file{hello-generic.c} were conditionally included in @code{hello}, the @file{Makefile.am} would contain: @example bin_PROGRAMS = hello hello_SOURCES = hello-common.c EXTRA_hello_SOURCES = hello-linux.c hello-generic.c hello_LDADD = $(HELLO_SYSTEM) hello_DEPENDENCIES = $(HELLO_SYSTEM) @end example @noindent You can then setup the @code{$(HELLO_SYSTEM)} substitution from @file{configure.ac}: @example @dots{} case $host in *linux*) HELLO_SYSTEM='hello-linux.$(OBJEXT)' ;; *) HELLO_SYSTEM='hello-generic.$(OBJEXT)' ;; esac AC_SUBST([HELLO_SYSTEM]) @dots{} @end example In this case, @code{HELLO_SYSTEM} should be replaced by @file{hello-linux.o} or @file{hello-generic.o}, and added to @code{hello_DEPENDENCIES} and @code{hello_LDADD} in order to be built and linked in. @subsubsection Conditional compilation using Automake conditionals An often simpler way to compile source files conditionally is to use Automake conditionals. For instance, you could use this @file{Makefile.am} construct to build the same @file{hello} example: @example bin_PROGRAMS = hello if LINUX hello_SOURCES = hello-linux.c hello-common.c else hello_SOURCES = hello-generic.c hello-common.c endif @end example In this case, your @file{configure.ac} should setup the @code{LINUX} conditional using @code{AM_CONDITIONAL} (@pxref{Conditionals}). When using conditionals like this you don't need to use the @samp{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 @code{+=}. @example bin_PROGRAMS = hello hello_SOURCES = hello-common.c if LINUX hello_SOURCES += hello-linux.c else hello_SOURCES += hello-generic.c endif @end example @node Conditional Programs @subsection Conditional compilation of programs @cindex Conditional programs @cindex Programs, conditional Sometimes it is useful to determine the programs that are to be built at configure time. For instance, GNU @code{cpio} only builds @code{mt} and @code{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. @subsubsection Conditional programs using @code{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 @file{Makefile.in} to use the programs specified by @code{configure}. This is done by having @code{configure} substitute values into each @samp{_PROGRAMS} definition, while listing all optionally built programs in @code{EXTRA_PROGRAMS}. @vindex EXTRA_PROGRAMS @cindex EXTRA_PROGRAMS, defined @example bin_PROGRAMS = cpio pax $(MT) libexec_PROGRAMS = $(RMT) EXTRA_PROGRAMS = mt rmt @end example As explained in @ref{EXEEXT}, Automake will rewrite @code{bin_PROGRAMS}, @code{libexec_PROGRAMS}, and @code{EXTRA_PROGRAMS}, appending @code{$(EXEEXT)} to each binary. Obviously it cannot rewrite values obtained at run-time through @code{configure} substitutions, therefore you should take care of appending @code{$(EXEEXT)} yourself, as in @code{AC_SUBST([MT], ['mt$@{EXEEXT@}'])}. @subsubsection Conditional programs using Automake conditionals You can also use Automake conditionals (@pxref{Conditionals}) to select programs to be built. In this case you don't have to worry about @code{$(EXEEXT)} or @code{EXTRA_PROGRAMS}. @example bin_PROGRAMS = cpio pax if WANT_MT bin_PROGRAMS += mt endif if WANT_RMT libexec_PROGRAMS = rmt endif @end example @node A Library @section Building a library @cindex _LIBRARIES primary, defined @cindex LIBRARIES primary, defined @cindex Primary variable, LIBRARIES @vindex lib_LIBRARIES @vindex pkglib_LIBRARIES @vindex noinst_LIBRARIES Building a library is much like building a program. In this case, the name of the primary is @samp{LIBRARIES}. Libraries can be installed in @code{libdir} or @code{pkglibdir}. @xref{A Shared Library}, for information on how to build shared libraries using libtool and the @samp{LTLIBRARIES} primary. Each @samp{_LIBRARIES} variable is a list of the libraries to be built. For instance to create a library named @file{libcpio.a}, but not install it, you would write: @example noinst_LIBRARIES = libcpio.a @end example The sources that go into a library are determined exactly as they are for programs, via the @samp{_SOURCES} variables. Note that the library name is canonicalized (@pxref{Canonicalization}), so the @samp{_SOURCES} variable corresponding to @file{liblob.a} is @samp{liblob_a_SOURCES}, not @samp{liblob.a_SOURCES}. @cindex _LIBADD primary, defined @cindex LIBADD primary, defined @cindex Primary variable, LIBADD Extra objects can be added to a library using the @samp{@var{library}_LIBADD} variable. This should be used for objects determined by @code{configure}. Again from @code{cpio}: @vindex _LIBADD @vindex LIBADD @example libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA) @end example In addition, sources for extra objects that will not exist until configure-time must be added to the @code{BUILT_SOURCES} variable (@pxref{Sources}). Building a static library is done by compiling all object files, then by invoking @code{$(AR) $(ARFLAGS)} followed by the name of the library and the list of objects, and finally by calling @code{$(RANLIB)} on that library. You should call @code{AC_PROG_RANLIB} from your @file{configure.ac} to define @code{RANLIB} (Automake will complain otherwise). @code{AR} and @code{ARFLAGS} default to @code{ar} and @code{cru} respectively; you can override these two variables my setting them in your @file{Makefile.am}, by @code{AC_SUBST}ing them from your @file{configure.ac}, or by defining a per-library @code{maude_AR} variable (@pxref{Program and Library Variables}). @node A Shared Library @section Building a Shared Library @cindex Shared libraries, support for Building shared libraries portably is a relatively complex matter. For this reason, GNU Libtool (@pxref{Top, , Introduction, libtool, The Libtool Manual}) was created to help build shared libraries in a platform-independent way. @menu * Libtool Concept:: Introducing Libtool * Libtool Libraries:: Declaring Libtool Libraries * Conditional Libtool Libraries:: Building Libtool Libraries Conditionally * Conditional Libtool Sources:: Choosing Library Sources Conditionally * Libtool Convenience Libraries:: Building Convenience Libtool Libraries * Libtool Modules:: Building Libtool Modules * Libtool Flags:: Using _LIBADD and _LDFLAGS * LTLIBOBJ:: Using $(LTLIBOBJ) * Libtool Issues:: Common Issues Related to Libtool's Use @end menu @node Libtool Concept @subsection The Libtool Concept @cindex libtool, introduction @cindex libtool library, definition @cindex suffix .la, defined @cindex .la suffix, defined Libtool abstracts shared and static libraries into a unified concept henceforth called @dfn{libtool libraries}. Libtool libraries are files using the @file{.la} suffix, and can designate a static library, a shared library, or maybe both. Their exact nature cannot be determined until @file{./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, @xref{AC_PROG_LIBTOOL, , The @code{AC_PROG_LIBTOOL} macro, libtool, The Libtool Manual}.) @cindex suffix .lo, defined 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 @dfn{libtool objects}: these are files using the @file{.lo} suffix. Libtool libraries are built from these libtool objects. You should not assume anything about the structure of @file{.la} or @file{.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 @file{Makefile}s rules 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 (@pxref{Conditional Libtool Sources}). @cindex libltdl, introduction People considering writing a plug-in system, with dynamically loaded modules, should look into @file{libltdl}: libtool's dlopening library (@pxref{Using libltdl, , Using libltdl, libtool, The Libtool Manual}). 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 (@pxref{Using Automake, , Using Automake with Libtool, libtool, The Libtool Manual}). @node Libtool Libraries @subsection Building Libtool Libraries @cindex _LTLIBRARIES primary, defined @cindex LTLIBRARIES primary, defined @cindex Primary variable, LTLIBRARIES @cindex Example of shared libraries @vindex lib_LTLIBRARIES @vindex pkglib_LTLIBRARIES Automake uses libtool to build libraries declared with the @samp{LTLIBRARIES} primary. Each @samp{_LTLIBRARIES} variable is a list of libtool libraries to build. For instance, to create a libtool library named @file{libgettext.la}, and install it in @samp{libdir}, write: @example lib_LTLIBRARIES = libgettext.la libgettext_la_SOURCES = gettext.c gettext.h @dots{} @end example Automake predefines the variable @samp{pkglibdir}, so you can use @code{pkglib_LTLIBRARIES} to install libraries in @code{$(libdir)/@@PACKAGE@@/}. @node Conditional Libtool Libraries @subsection Building Libtool Libraries Conditionally @cindex libtool libraries, conditional @cindex conditional libtool libraries Like conditional programs (@pxref{Conditional Programs}), there are two main ways to build conditional libraries: using Automake conditionals or using Autoconf @code{AC_SUBST}itutions. 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 @emph{at link-time} using the @code{-rpath} option. For libraries whose destination directory is known when Automake runs, Automake will automatically supply the appropriate @samp{-rpath} option to libtool. This is the case for libraries listed explicitly in some installable @code{_LTLIBRARIES} variables such as @code{lib_LTLIBRARIES}. However, for libraries determined at configure time (and thus mentioned in @code{EXTRA_LTLIBRARIES}), Automake does not know the final installation directory. For such libraries you must add the @samp{-rpath} option to the appropriate @samp{_LDFLAGS} variable by hand. The examples below illustrate the differences between these two methods. Here is an example where @code{$(WANTEDLIBS)} is an @code{AC_SUBST}ed variable set at @file{./configure}-time to either @file{libfoo.la}, @file{libbar.la}, both, or none. Although @code{$(WANTEDLIBS)} appears in the @code{lib_LTLIBRARIES}, Automake cannot guess it relates to @file{libfoo.la} or @file{libbar.la} by the time it creates the link rule for these two libraries. Therefore the @code{-rpath} argument must be explicitly supplied. @example EXTRA_LTLIBRARIES = libfoo.la libbar.la lib_LTLIBRARIES = $(WANTEDLIBS) libfoo_la_SOURCES = foo.c @dots{} libfoo_la_LDFLAGS = -rpath '$(libdir)' libbar_la_SOURCES = bar.c @dots{} libbar_la_LDFLAGS = -rpath '$(libdir)' @end example Here is how the same @file{Makefile.am} would look using Automake conditionals named @code{WANT_LIBFOO} and @code{WANT_LIBBAR}. Now Automake is able to compute the @code{-rpath} setting itself, because it's clear that both libraries will end up in @code{$(libdir)} if they are installed. @example lib_LTLIBRARIES = if WANT_LIBFOO lib_LTLIBRARIES += libfoo.la endif if WANT_LIBBAR lib_LTLIBRARIES += libbar.la endif libfoo_la_SOURCES = foo.c @dots{} libbar_la_SOURCES = bar.c @dots{} @end example @node Conditional Libtool Sources @subsection Libtool Libraries with Conditional Sources Conditional compilation of sources in a library can be achieved in the same way as conditional compilation of sources in a program (@pxref{Conditional Sources}). The only difference is that @code{_LIBADD} should be used instead of @code{_LDADD} and that it should mention libtool objects (@file{.lo} files). So, to mimic the @file{hello} example from @ref{Conditional Sources}, we could build a @file{libhello.la} library using either @file{hello-linux.c} or @file{hello-generic.c} with the following @file{Makefile.am}. @example 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 = $(HELLO_SYSTEM) @end example @noindent And make sure @code{$(HELLO_SYSTEM)} is set to either @file{hello-linux.lo} or @file{hello-generic.lo} in @file{./configure}. Or we could simply use an Automake conditional as follows. @example 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 @end example @node Libtool Convenience Libraries @subsection Libtool Convenience Libraries @cindex convenience libraries, libtool @cindex libtool convenience libraries @vindex noinst_LTLIBRARIES @vindex check_LTLIBRARIES Sometimes you want to build libtool libraries which should not be installed. These are called @dfn{libtool convenience libraries} and are typically used to encapsulate many sublibraries, later gathered into one big installed library. Libtool convenience libraries are declared by @code{noinst_LTLIBRARIES}, @code{check_LTLIBRARIES}, or even @code{EXTRA_LTLIBRARIES}. Unlike installed libtool libraries they do not need an @code{-rpath} flag at link time (actually this is the only difference). Convenience libraries listed in @code{noinst_LTLIBRARIES} are always built. Those listed in @code{check_LTLIBRARIES} are built only upon @code{make check}. Finally, libraries listed in @code{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 @code{EXTRA_LTLIBRARIES} is used for conditional compilation). Here is a sample setup merging libtool convenience libraries from subdirectories into one main @file{libtop.la} library. @example # -- Top-level Makefile.am -- SUBDIRS = sub1 sub2 @dots{} lib_LTLIBRARIES = libtop.la libtop_la_SOURCES = libtop_la_LIBADD = \ sub1/libsub1.la \ sub2/libsub2.la \ @dots{} # -- sub1/Makefile.am -- noinst_LTLIBRARIES = libsub1.la libsub1_la_SOURCES = @dots{} # -- sub2/Makefile.am -- # showing nested convenience libraries SUBDIRS = sub2.1 sub2.2 @dots{} noinst_LTLIBRARIES = libsub2.la libsub2_la_SOURCES = libsub2_la_LIBADD = \ sub21/libsub21.la \ sub22/libsub22.la \ @dots{} @end example @node Libtool Modules @subsection Libtool Modules @cindex modules, libtool @cindex libtool modules @cindex -module, libtool These are libtool libraries meant to be dlopened. They are indicated to libtool by passing @code{-module} at link-time. @example pkglib_LTLIBRARIES = mymodule.la mymodule_la_SOURCES = doit.c mymodule_la_LDFLAGS = -module @end example Ordinarily, Automake requires that a Library's name starts with @samp{lib}. However, when building a dynamically loadable module you might wish to use a "nonstandard" name. If @samp{mymodule_la_SOURCES} is not specified, then it defaults to the single file @file{mymodule.c} (@pxref{Default _SOURCES}). @node Libtool Flags @subsection _LIBADD and _LDFLAGS @cindex _LIBADD, libtool @cindex _LDFLAGS, libtool As shown in previous sections, the @samp{@var{library}_LIBADD} variable should be used to list extra libtool objects (@file{.lo} files) or libtool libraries (@file{.la}) to add to @var{library}. The @samp{@var{library}_LDFLAGS} variable is the place to list additional libtool flags, such as @samp{-version-info}, @samp{-static}, and a lot more. See @xref{Link mode, , Using libltdl, libtool, The Libtool Manual}. @node LTLIBOBJ, Libtool Issues, Libtool Flags, A Shared Library @subsection @code{LTLIBOBJS} @cindex @code{LTLIBOBJS}, special handling @vindex LTLIBOBJS @vindex LIBOBJS @cvindex AC_LIBOBJ Where an ordinary library might include @code{$(LIBOBJS)}, a libtool library must use @code{$(LTLIBOBJS)}. This is required because the object files that libtool operates on do not necessarily end in @file{.o}. Nowadays, the computation of @code{LTLIBOBJS} from @code{LIBOBJS} is performed automatically by Autoconf (@pxref{AC_LIBOBJ vs LIBOBJS, , @code{AC_LIBOBJ} vs. @code{LIBOBJS}, autoconf, The Autoconf Manual}). @node Libtool Issues @subsection Common Issues Related to Libtool's Use @subsubsection @code{required file `./ltmain.sh' not found} @cindex ltmain.sh not found @cindex libtoolize, no longer run by Automake @cindex libtoolize and autoreconf @cindex autoreconf and libtoolize @cindex bootstrap.sh and autoreconf @cindex autogen.sh and autoreconf Libtool comes with a tool called @command{libtoolize} that will install libtool's supporting files into a package. Running this command will install @file{ltmain.sh}. You should execute it before @command{aclocal} and @command{automake}. People upgrading old packages to newer autotools are likely to face this issue because older Automake versions used to call @command{libtoolize}. Therefore old build scripts do not call @command{libtoolize}. Since Automake 1.6, it has been decided that running @command{libtoolize} was none of Automake's business. Instead, that functionality has been moved into the @command{autoreconf} command (@pxref{autoreconf Invocation, , Using @command{autoreconf}, autoconf, The Autoconf Manual}). If you do not want to remember what to run and when, just learn the @command{autoreconf} command. Hopefully, replacing existing @file{bootstrap.sh} or @file{autogen.sh} scripts by a call to @command{autoreconf} should also free you from any similar incompatible change in the future. @subsubsection Objects @code{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 @file{Makefile.am}. @example bin_PROGRAMS = prog prog_SOURCES = prog.c foo.c @dots{} lib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = foo.c @dots{} @end example @noindent (In this trivial case the issue could be avoided by linking @file{libfoo.la} with @file{prog} instead of listing @file{foo.c} in @code{prog_SOURCES}. But let's assume we really want to keep @file{prog} and @file{libfoo.la} separate.) Technically, it means that we should build @file{foo.$(OBJEXT)} for @file{prog}, and @file{foo.lo} for @file{libfoo.la}. The problem is that in the course of creating @file{foo.lo}, libtool may erase (or replace) @file{foo.$(OBJEXT)} -- and this cannot be avoided. Therefore, when Automake detects this situation it will complain with a message such as @example object `foo.$(OBJEXT)' created both with libtool and without @end example A workaround for this issue is to ensure that these two objects get different basenames. As explained in @ref{renamed objects}, this happens automatically when per-targets flags are used. @example bin_PROGRAMS = prog prog_SOURCES = prog.c foo.c @dots{} prog_CFLAGS = $(AM_CFLAGS) lib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = foo.c @dots{} @end example @noindent Adding @code{prog_CFLAGS = $(AM_CFLAGS)} is almost a no-op, because when the @code{prog_CFLAGS} is defined, it is used instead of @code{AM_CFLAGS}. However as a side effect it will cause @file{prog.c} and @file{foo.c} to be compiled as @file{prog-prog.$(OBJEXT)} and @file{prog-foo.$(OBJEXT)} which solves the issue. @node Program and Library Variables @section Program and Library Variables 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 @file{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. @table @samp @item maude_SOURCES This variable, if it exists, lists all the source files which are compiled to build the program. These files are added to the distribution by default. When building the program, Automake will cause each source file to be compiled to a single @file{.o} file (or @file{.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 @samp{_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 @file{.o} files, then automake will treat this file as it will any other source file (@pxref{Support for Other Languages}). Otherwise, the file will be ignored as though it were a header file. The prefixes @samp{dist_} and @samp{nodist_} can be used to control whether files listed in a @samp{_SOURCES} variable are distributed. @samp{dist_} is redundant, as sources are distributed by default, but it can be specified for clarity if desired. It is possible to have both @samp{dist_} and @samp{nodist_} variants of a given @samp{_SOURCES} variable at once; this lets you easily distribute some files and not others, for instance: @example nodist_maude_SOURCES = nodist.c dist_maude_SOURCES = dist-me.c @end example By default the output file (on Unix systems, the @file{.o} file) will be put into the current build directory. However, if the option @code{subdir-objects} is in effect in the current directory then the @file{.o} file will be put into the subdirectory named after the source file. For instance, with @code{subdir-objects} enabled, @file{sub/dir/file.c} will be compiled to @file{sub/dir/file.o}. Some people prefer this mode of operation. You can specify @code{subdir-objects} in @code{AUTOMAKE_OPTIONS} (@pxref{Options}). @cindex Subdirectory, objects in @cindex Objects in subdirectory @item EXTRA_maude_SOURCES Automake needs to know the list of files you intend to compile @emph{statically}. For one thing, this is the only way Automake has of knowing what sort of language support a given @file{Makefile.in} requires. @footnote{There are other, more obscure reasons for this limitation as well.} This means that, for example, you can't put a configure substitution like @samp{@@my_sources@@} into a @samp{_SOURCES} variable. If you intend to conditionally compile source files and use @file{configure} to substitute the appropriate object names into, e.g., @samp{_LDADD} (see below), then you should list the corresponding source files in the @samp{EXTRA_} variable. This variable also supports @samp{dist_} and @samp{nodist_} prefixes, e.g., @samp{nodist_EXTRA_maude_SOURCES}. @item maude_AR A static library is created by default by invoking @code{$(AR) $(ARFLAGS)} followed by the name of the library and then the objects being put into the library. You can override this by setting the @samp{_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: @example libmaude_a_AR = $(CXX) -ar -o @end example @item maude_LIBADD Extra objects can be added to a @emph{library} using the @samp{_LIBADD} variable. For instance this should be used for objects determined by @code{configure} (@pxref{A Library}). @item maude_LDADD Extra objects can be added to a @emph{program} by listing them in the @samp{_LDADD} variable. For instance this should be used for objects determined by @code{configure} (@pxref{Linking}). @samp{_LDADD} and @samp{_LIBADD} are inappropriate for passing program-specific linker flags (except for @samp{-l}, @samp{-L}, @samp{-dlopen} and @samp{-dlpreopen}). Use the @samp{_LDFLAGS} variable for this purpose. For instance, if your @file{configure.ac} uses @code{AC_PATH_XTRA}, you could link your program against the X libraries like so: @example maude_LDADD = $(X_PRE_LIBS) $(X_LIBS) $(X_EXTRA_LIBS) @end example @item maude_LDFLAGS This variable is used to pass extra flags to the link step of a program or a shared library. @item maude_DEPENDENCIES It is also occasionally useful to have a program depend on some other target which is not actually part of that program. This can be done using the @samp{_DEPENDENCIES} variable. Each program depends on the contents of such a variable, but no further interpretation is done. If @samp{_DEPENDENCIES} is not supplied, it is computed by Automake. The automatically-assigned value is the contents of @samp{_LDADD} or @samp{_LIBADD}, with most configure substitutions, @samp{-l}, @samp{-L}, @samp{-dlopen} and @samp{-dlpreopen} options removed. The configure substitutions that are left in are only @samp{$(LIBOBJS)} and @samp{$(ALLOCA)}; these are left because it is known that they will not cause an invalid value for @samp{_DEPENDENCIES} to be generated. @item maude_LINK You can override the linker on a per-program basis. By default the linker is chosen according to the languages used by the program. For instance, a program that includes C++ source code would use the C++ compiler to link. The @samp{_LINK} variable must hold the name of a command which can be passed all the @file{.o} file names as arguments. Note that the name of the underlying program is @emph{not} passed to @samp{_LINK}; typically one uses @samp{$@@}: @example maude_LINK = $(CCLD) -magic -o $@@ @end example @item maude_CCASFLAGS @itemx maude_CFLAGS @itemx maude_CPPFLAGS @itemx maude_CXXFLAGS @itemx maude_FFLAGS @itemx maude_GCJFLAGS @itemx maude_LFLAGS @itemx maude_OBJCFLAGS @itemx maude_RFLAGS @itemx maude_YFLAGS @cindex per-target compilation flags, defined Automake allows you to set compilation flags on a per-program (or per-library) basis. A single source file can be included in several programs, and it will potentially be compiled with different flags for each program. This works for any language directly supported by Automake. These @dfn{per-target compilation flags} are @samp{_CCASFLAGS}, @samp{_CFLAGS}, @samp{_CPPFLAGS}, @samp{_CXXFLAGS}, @samp{_FFLAGS}, @samp{_GCJFLAGS}, @samp{_LFLAGS}, @samp{_OBJCFLAGS}, @samp{_RFLAGS}, and @samp{_YFLAGS}. When using a per-target compilation flag, Automake will choose a different name for the intermediate object files. Ordinarily a file like @file{sample.c} will be compiled to produce @file{sample.o}. However, if the program's @samp{_CFLAGS} variable is set, then the object file will be named, for instance, @file{maude-sample.o}. (See also @ref{renamed objects}.) In compilations with per-target flags, the ordinary @samp{AM_} form of the flags variable is @emph{not} automatically included in the compilation (however, the user form of the variable @emph{is} included). So for instance, if you want the hypothetical @file{maude} compilations to also use the value of @samp{AM_CFLAGS}, you would need to write: @example maude_CFLAGS = @dots{} your flags @dots{} $(AM_CFLAGS) @end example @item maude_SHORTNAME On some platforms the allowable file names are very short. In order to support these systems and per-target compilation flags at the same time, Automake allows you to set a ``short name'' which will influence how intermediate object files are named. For instance, in the following example, @example bin_PROGRAMS = maude maude_CPPFLAGS = -DSOMEFLAG maude_SHORTNAME = m maude_SOURCES = sample.c @dots{} @end example @noindent the object file would be named @file{m-sample.o} rather than @file{maude-sample.o}. This facility is rarely needed in practice, and we recommend avoiding it until you find it is required. @end table @node Default _SOURCES @section Default @code{_SOURCES} @vindex _SOURCES @vindex SOURCES @cindex @code{_SOURCES}, default @cindex default @code{_SOURCES} @code{_SOURCES} variables are used to specify source files of programs (@pxref{A Program}), libraries (@pxref{A Library}), and Libtool libraries (@pxref{A Shared Library}). When no such variable is specified for a target, Automake will define one itself. The default is to compile a single C file whose base name is the name of the target itself, with any extension replaced by @file{.c}. (Defaulting to C is terrible but we are stuck with it for historical reasons.) For example if you have the following somewhere in your @file{Makefile.am} with no corresponding @samp{libfoo_a_SOURCES}: @example lib_LIBRARIES = libfoo.a sub/libc++.a @end example @noindent @file{libfoo.a} will be built using a default source file named @file{libfoo.c}, and @file{sub/libc++.a} will be built from @file{sub/libc++.c}. (In older versions @file{sub/libc++.a} would be built from @file{sub_libc___a.c}, i.e., the default source was the canonized name of the target, with @file{.c} appended. We believe the new behavior is more sensible, but for backward compatibility automake will use the old name if a file or a rule with that name exist.) @cindex @code{check_PROGRAMS} example @vindex check_PROGRAMS Default sources are mainly useful in test suites, when building many tests programs each from a single source. For instance in @example check_PROGRAMS = test1 test2 test3 @end example @noindent @file{test1}, @file{test2}, and @file{test3} will be built from @file{test1.c}, @file{test2.c}, and @file{test3.c}. @cindex Libtool modules, default source example @cindex default source, Libtool modules example Another case where is this convenient is building many Libtool modules (@file{moduleN.la}), each defined in its own file (@file{moduleN.c}). @example AM_LDFLAGS = -module lib_LTLIBRARIES = module1.la module2.la module3.la @end example @cindex empty @code{_SOURCES} @cindex @code{_SOURCES}, empty Finally, there is one situation where this default source computation needs to be avoided: when a target should not be built from sources. We already saw such an example in @ref{true}; this happens when all the constituents of a target have already been compiled and need just to be combined using a @code{_LDADD} variable. Then it is necessary to define an empty @code{_SOURCES} variable, so that automake does not compute a default. @example bin_PROGRAMS = target target_SOURCES = target_LDADD = libmain.a libmisc.a @end example @node LIBOBJS @section Special handling for LIBOBJS and ALLOCA @cindex @code{LIBOBJS}, special handling @cindex @code{ALLOCA}, special handling Automake explicitly recognizes the use of @code{$(LIBOBJS)} and @code{$(ALLOCA)}, and uses this information, plus the list of @code{LIBOBJS} files derived from @file{configure.ac} to automatically include the appropriate source files in the distribution (@pxref{Dist}). These source files are also automatically handled in the dependency-tracking scheme; see @xref{Dependencies}. @code{$(LIBOBJS)} and @code{$(ALLOCA)} are specially recognized in any @samp{_LDADD} or @samp{_LIBADD} variable. @node Program variables @section Variables used when building a program Occasionally it is useful to know which @file{Makefile} variables Automake uses for compilations; for instance you might need to do your own compilation in some special cases. Some variables are inherited from Autoconf; these are @code{CC}, @code{CFLAGS}, @code{CPPFLAGS}, @code{DEFS}, @code{LDFLAGS}, and @code{LIBS}. @vindex CC @vindex CFLAGS @vindex CPPFLAGS @vindex DEFS @vindex LDFLAGS @vindex LIBS There are some additional variables which Automake itself defines: @vtable @code @item AM_CPPFLAGS The contents of this variable are passed to every compilation which invokes the C preprocessor; it is a list of arguments to the preprocessor. For instance, @samp{-I} and @samp{-D} options should be listed here. Automake already provides some @samp{-I} options automatically. In particular it generates @samp{-I$(srcdir)}, @samp{-I.}, and a @samp{-I} pointing to the directory holding @file{config.h} (if you've used @code{AC_CONFIG_HEADERS} or @code{AM_CONFIG_HEADER}). You can disable the default @samp{-I} options using the @samp{nostdinc} option. @code{AM_CPPFLAGS} is ignored in preference to a per-executable (or per-library) @code{_CPPFLAGS} variable if it is defined. @item INCLUDES This does the same job as @samp{AM_CPPFLAGS} (or any per-target @samp{_CPPFLAGS} variable if it is used). It is an older name for the same functionality. This variable is deprecated; we suggest using @samp{AM_CPPFLAGS} and per-target @samp{_CPPFLAGS} instead. @item AM_CFLAGS This is the variable which the @file{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) @code{_CFLAGS}. @item COMPILE This is the command used to actually compile a C source file. The filename is appended to form the complete command line. @item AM_LDFLAGS This is the variable which the @file{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) @code{_LDFLAGS}. @item LINK This is the command used to actually link a C program. It already includes @samp{-o $@@} and the usual variable references (for instance, @code{CFLAGS}); it takes as ``arguments'' the names of the object files and libraries to link in. @end vtable @node Yacc and Lex @section Yacc and Lex support Automake has somewhat idiosyncratic support for Yacc and Lex. Automake assumes that the @file{.c} file generated by @code{yacc} (or @code{lex}) should be named using the basename of the input file. That is, for a yacc source file @file{foo.y}, Automake will cause the intermediate file to be named @file{foo.c} (as opposed to @file{y.tab.c}, which is more traditional). The extension of a yacc source file is used to determine the extension of the resulting @samp{C} or @samp{C++} file. Files with the extension @samp{.y} will be turned into @samp{.c} files; likewise, @samp{.yy} will become @samp{.cc}; @samp{.y++}, @samp{c++}; and @samp{.yxx}, @samp{.cxx}. Likewise, lex source files can be used to generate @samp{C} or @samp{C++}; the extensions @samp{.l}, @samp{.ll}, @samp{.l++}, and @samp{.lxx} are recognized. You should never explicitly mention the intermediate (@samp{C} or @samp{C++}) file in any @samp{SOURCES} variable; only list the source file. The intermediate files generated by @code{yacc} (or @code{lex}) will be included in any distribution that is made. That way the user doesn't need to have @code{yacc} or @code{lex}. If a @code{yacc} source file is seen, then your @file{configure.ac} must define the variable @samp{YACC}. This is most easily done by invoking the macro @samp{AC_PROG_YACC} (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}). When @code{yacc} is invoked, it is passed @samp{YFLAGS} and @samp{AM_YFLAGS}. The former is a user variable and the latter is intended for the @file{Makefile.am} author. @samp{AM_YFLAGS} is usually used to pass the @code{-d} option to @code{yacc}. Automake knows what this means and will automatically adjust its rules to update and distribute the header file built by @code{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 @code{BUILT_SOURCES} (@pxref{Sources}) as follows. @example BUILT_SOURCES = parser.h AM_YFLAGS = -d bin_PROGRAMS = foo foo_SOURCES = @dots{} parser.y @dots{} @end example If a @code{lex} source file is seen, then your @file{configure.ac} must define the variable @samp{LEX}. You can use @samp{AC_PROG_LEX} to do this (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}), but using @code{AM_PROG_LEX} macro (@pxref{Macros}) is recommended. When @code{lex} is invoked, it is passed @samp{LFLAGS} and @samp{AM_LFLAGS}. The former is a user variable and the latter is intended for the @file{Makefile.am} author. @cindex ylwrap @cindex yacc, multiple parsers @cindex Multiple yacc parsers @cindex Multiple lex lexers @cindex lex, multiple lexers Automake makes it possible to include multiple @code{yacc} (or @code{lex}) source files in a single program. When there is more than one distinct @code{yacc} (or @code{lex}) source file in a directory, Automake uses a small program called @code{ylwrap} to run @code{yacc} (or @code{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 @code{yacc} simultaneously. The @code{ylwrap} program is distributed with Automake. It should appear in the directory specified by @samp{AC_CONFIG_AUX_DIR} (@pxref{Input, , Finding `configure' Input, autoconf, The Autoconf Manual}), or the current directory if that macro is not used in @file{configure.ac}. For @code{yacc}, simply managing locking is insufficient. The output of @code{yacc} always uses the same symbol names internally, so it isn't possible to link two @code{yacc} parsers into the same executable. We recommend using the following renaming hack used in @code{gdb}: @example #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 @end example For each define, replace the @samp{c_} prefix with whatever you like. These defines work for @code{bison}, @code{byacc}, and traditional @code{yacc}s. 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. @node C++ Support @section C++ Support @cindex C++ support @cindex Support for C++ Automake includes full support for C++. Any package including C++ code must define the output variable @samp{CXX} in @file{configure.ac}; the simplest way to do this is to use the @code{AC_PROG_CXX} macro (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}). A few additional variables are defined when a C++ source file is seen: @vtable @code @item CXX The name of the C++ compiler. @item CXXFLAGS Any flags to pass to the C++ compiler. @item AM_CXXFLAGS The maintainer's variant of @code{CXXFLAGS}. @item CXXCOMPILE The command used to actually compile a C++ source file. The file name is appended to form the complete command line. @item CXXLINK The command used to actually link a C++ program. @end vtable @node Assembly Support @section Assembly Support Automake includes some support for assembly code. The variable @code{CCAS} holds the name of the compiler used to build assembly code. This compiler must work a bit like a C compiler; in particular it must accept @samp{-c} and @samp{-o}. The value of @code{CCASFLAGS} is passed to the compilation. @vindex CCAS @vindex CCASFLAGS You are required to set @code{CCAS} and @code{CCASFLAGS} via @file{configure.ac}. The autoconf macro @code{AM_PROG_AS} will do this for you. Unless they are already set, it simply sets @code{CCAS} to the C compiler and @code{CCASFLAGS} to the C compiler flags. Only the suffixes @samp{.s} and @samp{.S} are recognized by @code{automake} as being files containing assembly code. @node Fortran 77 Support @comment node-name, next, previous, up @section Fortran 77 Support @cindex Fortran 77 support @cindex Support for Fortran 77 Automake includes full support for Fortran 77. Any package including Fortran 77 code must define the output variable @samp{F77} in @file{configure.ac}; the simplest way to do this is to use the @code{AC_PROG_F77} macro (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}). A few additional variables are defined when a Fortran 77 source file is seen: @vtable @code @item F77 The name of the Fortran 77 compiler. @item FFLAGS Any flags to pass to the Fortran 77 compiler. @item AM_FFLAGS The maintainer's variant of @code{FFLAGS}. @item RFLAGS Any flags to pass to the Ratfor compiler. @item AM_RFLAGS The maintainer's variant of @code{RFLAGS}. @item F77COMPILE The command used to actually compile a Fortran 77 source file. The file name is appended to form the complete command line. @item FLINK The command used to actually link a pure Fortran 77 program or shared library. @end vtable Automake can handle preprocessing Fortran 77 and Ratfor source files in addition to compiling them@footnote{Much, if not most, of the information in the following sections pertaining to preprocessing Fortran 77 programs was taken almost verbatim from @ref{Catalogue of Rules, , Catalogue of Rules, make, The GNU Make Manual}.}. Automake also contains some support for creating programs and shared libraries that are a mixture of Fortran 77 and other languages (@pxref{Mixing Fortran 77 With C and C++}). These issues are covered in the following sections. @menu * Preprocessing Fortran 77:: Preprocessing Fortran 77 sources * Compiling Fortran 77 Files:: Compiling Fortran 77 sources * Mixing Fortran 77 With C and C++:: Mixing Fortran 77 With C and C++ @end menu @node Preprocessing Fortran 77 @comment node-name, next, previous, up @subsection Preprocessing Fortran 77 @cindex Preprocessing Fortran 77 @cindex Fortran 77, Preprocessing @cindex Ratfor programs @file{N.f} is made automatically from @file{N.F} or @file{N.r}. This rule runs just the preprocessor to convert a preprocessable Fortran 77 or Ratfor source file into a strict Fortran 77 source file. The precise command used is as follows: @table @file @item .F @code{$(F77) -F $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_FFLAGS) $(FFLAGS)} @item .r @code{$(F77) -F $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)} @end table @node Compiling Fortran 77 Files @comment node-name, next, previous, up @subsection Compiling Fortran 77 Files @file{N.o} is made automatically from @file{N.f}, @file{N.F} or @file{N.r} by running the Fortran 77 compiler. The precise command used is as follows: @table @file @item .f @code{$(F77) -c $(AM_FFLAGS) $(FFLAGS)} @item .F @code{$(F77) -c $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_FFLAGS) $(FFLAGS)} @item .r @code{$(F77) -c $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)} @end table @node Mixing Fortran 77 With C and C++ @comment node-name, next, previous, up @subsection Mixing Fortran 77 With C and C++ @cindex Fortran 77, mixing with C and C++ @cindex Mixing Fortran 77 with C and C++ @cindex Linking Fortran 77 with C and C++ @cindex cfortran @cindex Mixing Fortran 77 with C and/or C++ Automake currently provides @emph{limited} support for creating programs and shared libraries that are a mixture of Fortran 77 and C and/or C++. However, there are many other issues related to mixing Fortran 77 with other languages that are @emph{not} (currently) handled by Automake, but that are handled by other packages@footnote{For example, @uref{http://www-zeus.desy.de/~burow/cfortran/, the cfortran package} addresses all of these inter-language issues, and runs under nearly all Fortran 77, C and C++ compilers on nearly all platforms. However, @code{cfortran} is not yet Free Software, but it will be in the next major release.}. @page Automake can help in two ways: @enumerate @item Automatic selection of the linker depending on which combinations of source code. @item Automatic selection of the appropriate linker flags (e.g. @samp{-L} and @samp{-l}) to pass to the automatically selected linker in order to link in the appropriate Fortran 77 intrinsic and run-time libraries. @cindex FLIBS, defined These extra Fortran 77 linker flags are supplied in the output variable @code{FLIBS} by the @code{AC_F77_LIBRARY_LDFLAGS} Autoconf macro supplied with newer versions of Autoconf (Autoconf version 2.13 and later). @xref{Fortran 77 Compiler Characteristics, , , autoconf, The Autoconf}. @end enumerate If Automake detects that a program or shared library (as mentioned in some @code{_PROGRAMS} or @code{_LTLIBRARIES} primary) contains source code that is a mixture of Fortran 77 and C and/or C++, then it requires that the macro @code{AC_F77_LIBRARY_LDFLAGS} be called in @file{configure.ac}, and that either @code{$(FLIBS)} appear in the appropriate @code{_LDADD} (for programs) or @code{_LIBADD} (for shared libraries) variables. It is the responsibility of the person writing the @file{Makefile.am} to make sure that @code{$(FLIBS)} appears in the appropriate @code{_LDADD} or @code{_LIBADD} variable. @cindex Mixed language example @cindex Example, mixed language For example, consider the following @file{Makefile.am}: @example bin_PROGRAMS = foo foo_SOURCES = main.cc foo.f foo_LDADD = libfoo.la $(FLIBS) pkglib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = bar.f baz.c zardoz.cc libfoo_la_LIBADD = $(FLIBS) @end example In this case, Automake will insist that @code{AC_F77_LIBRARY_LDFLAGS} is mentioned in @file{configure.ac}. Also, if @code{$(FLIBS)} hadn't been mentioned in @code{foo_LDADD} and @code{libfoo_la_LIBADD}, then Automake would have issued a warning. @page @menu * How the Linker is Chosen:: Automatic linker selection @end menu @node How the Linker is Chosen @comment node-name, next, previous, up @subsubsection How the Linker is Chosen @cindex Automatic linker selection @cindex Selecting the linker automatically The following diagram demonstrates under what conditions a particular linker is chosen by Automake. For example, if Fortran 77, C and C++ source code were to be compiled into a program, then the C++ linker will be used. In this case, if the C or Fortran 77 linkers required any special libraries that weren't included by the C++ linker, then they must be manually added to an @code{_LDADD} or @code{_LIBADD} variable by the user writing the @file{Makefile.am}. @example \ Linker source \ code \ C C++ Fortran ----------------- +---------+---------+---------+ | | | | C | x | | | | | | | +---------+---------+---------+ | | | | C++ | | x | | | | | | +---------+---------+---------+ | | | | Fortran | | | x | | | | | +---------+---------+---------+ | | | | C + C++ | | x | | | | | | +---------+---------+---------+ | | | | C + Fortran | | | x | | | | | +---------+---------+---------+ | | | | C++ + Fortran | | x | | | | | | +---------+---------+---------+ | | | | C + C++ + Fortran | | x | | | | | | +---------+---------+---------+ @end example @node Fortran 9x Support @comment node-name, next, previous, up @section Fortran 9x Support @cindex Fortran 9x support @cindex Support for Fortran 9x Automake includes full support for Fortran 9x. Any package including Fortran 9x code must define the output variable @samp{FC} in @file{configure.ac}; the simplest way to do this is to use the @code{AC_PROG_FC} macro (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}). A few additional variables are defined when a Fortran 9x source file is seen: @vtable @code @item FC The name of the Fortran 9x compiler. @item FCFLAGS Any flags to pass to the Fortran 9x compiler. @item AM_FCFLAGS The maintainer's variant of @code{FCFLAGS}. @item FCCOMPILE The command used to actually compile a Fortran 9x source file. The file name is appended to form the complete command line. @item FCLINK The command used to actually link a pure Fortran 9x program or shared library. @end vtable @menu * Compiling Fortran 9x Files:: Compiling Fortran 9x sources @end menu @node Compiling Fortran 9x Files @comment node-name, next, previous, up @subsection Compiling Fortran 9x Files @file{N.o} is made automatically from @file{N.f90} or @file{N.f95} by running the Fortran 9x compiler. The precise command used is as follows: @table @file @item .f9x @code{$(FC) -c $(AM_FCFLAGS) $(FCFLAGS)} @end table @node Java Support @comment node-name, next, previous, up @section Java Support @cindex Java support @cindex Support for Java Automake includes support for compiled Java, using @code{gcj}, the Java front end to the GNU Compiler Collection. Any package including Java code to be compiled must define the output variable @samp{GCJ} in @file{configure.ac}; the variable @samp{GCJFLAGS} must also be defined somehow (either in @file{configure.ac} or @file{Makefile.am}). The simplest way to do this is to use the @code{AM_PROG_GCJ} macro. @vindex GCJFLAGS By default, programs including Java source files are linked with @code{gcj}. As always, the contents of @samp{AM_GCJFLAGS} are passed to every compilation invoking @code{gcj} (in its role as an ahead-of-time compiler -- when invoking it to create @file{.class} files, @samp{AM_JAVACFLAGS} is used instead). If it is necessary to pass options to @code{gcj} from @file{Makefile.am}, this variable, and not the user variable @samp{GCJFLAGS}, should be used. @vindex AM_GCJFLAGS @code{gcj} can be used to compile @file{.java}, @file{.class}, @file{.zip}, or @file{.jar} files. When linking, @code{gcj} requires that the main class be specified using the @samp{--main=} option. The easiest way to do this is to use the @code{_LDFLAGS} variable for the program. @node Support for Other Languages @comment node-name, next, previous, up @section Support for Other Languages Automake currently only includes full support for C, C++ (@pxref{C++ Support}), Fortran 77 (@pxref{Fortran 77 Support}), Fortran 9x (@pxref{Fortran 9x Support}), and Java (@pxref{Java Support}). There is only rudimentary support for other languages, support for which will be improved based on user demand. Some limited support for adding your own languages is available via the suffix rule handling; see @ref{Suffixes}. @node ANSI @section Automatic de-ANSI-fication @cindex de-ANSI-fication, defined Although the GNU standards allow the use of ANSI C, this can have the effect of limiting portability of a package to some older compilers (notably the SunOS C compiler). Automake allows you to work around this problem on such machines by @dfn{de-ANSI-fying} each source file before the actual compilation takes place. @vindex AUTOMAKE_OPTIONS @opindex ansi2knr If the @file{Makefile.am} variable @code{AUTOMAKE_OPTIONS} (@pxref{Options}) contains the option @code{ansi2knr} then code to handle de-ANSI-fication is inserted into the generated @file{Makefile.in}. This causes each C source file in the directory to be treated as ANSI C@. If an ANSI C compiler is available, it is used. If no ANSI C compiler is available, the @code{ansi2knr} program is used to convert the source files into K&R C, which is then compiled. The @code{ansi2knr} program is simple-minded. It assumes the source code will be formatted in a particular way; see the @code{ansi2knr} man page for details. Support for de-ANSI-fication requires the source files @file{ansi2knr.c} and @file{ansi2knr.1} to be in the same package as the ANSI C source; these files are distributed with Automake. Also, the package @file{configure.ac} must call the macro @code{AM_C_PROTOTYPES} (@pxref{Macros}). @cvindex AM_C_PROTOTYPES Automake also handles finding the @code{ansi2knr} support files in some other directory in the current package. This is done by prepending the relative path to the appropriate directory to the @code{ansi2knr} option. For instance, suppose the package has ANSI C code in the @file{src} and @file{lib} subdirectories. The files @file{ansi2knr.c} and @file{ansi2knr.1} appear in @file{lib}. Then this could appear in @file{src/Makefile.am}: @example AUTOMAKE_OPTIONS = ../lib/ansi2knr @end example If no directory prefix is given, the files are assumed to be in the current directory. Note that automatic de-ANSI-fication will not work when the package is being built for a different host architecture. That is because automake currently has no way to build @code{ansi2knr} for the build machine. @c FIXME: this paragraph might be better moved to an `upgrading' section. @cindex @code{LTLIBOBJS} and @code{ansi2knr} @cindex @code{LIBOBJS} and @code{ansi2knr} @cindex @code{ansi2knr} and @code{LTLIBOBJS} @cindex @code{ansi2knr} and @code{LIBOBJS} Using @code{LIBOBJS} with source de-ANSI-fication used to require hand-crafted code in @file{configure} to append @code{$U} to basenames in @code{LIBOBJS}. This is no longer true today. Starting with version 2.54, Autoconf takes care of rewriting @code{LIBOBJS} and @code{LTLIBOBJS}. (@pxref{AC_LIBOBJ vs LIBOBJS, , @code{AC_LIBOBJ} vs. @code{LIBOBJS}, autoconf, The Autoconf Manual}) @node Dependencies @section Automatic dependency tracking As a developer it is often painful to continually update the @file{Makefile.in} whenever the include-file dependencies change in a project. Automake supplies a way to automatically track dependency changes. @cindex Dependency tracking @cindex Automatic dependency tracking Automake always uses complete dependencies for a compilation, including system headers. Automake's model is that dependency computation should be a side effect of the build. To this end, dependencies are computed by running all compilations through a special wrapper program called @code{depcomp}. @code{depcomp} understands how to coax many different C and C++ compilers into generating dependency information in the format it requires. @code{automake -a} will install @code{depcomp} into your source tree for you. If @code{depcomp} can't figure out how to properly invoke your compiler, dependency tracking will simply be disabled for your build. @cindex depcomp Experience with earlier versions of Automake @footnote{See @uref{http://sources.redhat.com/automake/dependencies.html} for more information on the history and experiences with automatic dependency tracking in Automake} taught us that it is not reliable to generate dependencies only on the maintainer's system, as configurations vary too much. So instead Automake implements dependency tracking at build time. Automatic dependency tracking can be suppressed by putting @code{no-dependencies} in the variable @code{AUTOMAKE_OPTIONS}, or passing @code{no-dependencies} as an argument to @code{AM_INIT_AUTOMAKE} (this should be the preferred way). Or, you can invoke @code{automake} with the @code{-i} option. Dependency tracking is enabled by default. @vindex AUTOMAKE_OPTIONS @opindex no-dependencies The person building your package also can choose to disable dependency tracking by configuring with @code{--disable-dependency-tracking}. @cindex Disabling dependency tracking @cindex Dependency tracking, disabling @node EXEEXT @section Support for executable extensions @cindex Executable extension @cindex Extension, executable @cindex Windows On some platforms, such as Windows, executables are expected to have an extension such as @samp{.exe}. On these platforms, some compilers (GCC among them) will automatically generate @file{foo.exe} when asked to generate @file{foo}. Automake provides mostly-transparent support for this. Unfortunately @emph{mostly} doesn't yet mean @emph{fully}. Until the English dictionary is revised, you will have to assist Automake if your package must support those platforms. One thing you must be aware of is that, internally, Automake rewrites something like this: @example bin_PROGRAMS = liver @end example to this: @example bin_PROGRAMS = liver$(EXEEXT) @end example The targets Automake generates are likewise given the @samp{$(EXEEXT)} extension. @code{EXEEXT} However, Automake cannot apply this rewriting to @code{configure} substitutions. This means that if you are conditionally building a program using such a substitution, then your @file{configure.ac} must take care to add @samp{$(EXEEXT)} when constructing the output variable. With Autoconf 2.13 and earlier, you must explicitly use @code{AC_EXEEXT} to get this support. With Autoconf 2.50, @code{AC_EXEEXT} is run automatically if you configure a compiler (say, through @code{AC_PROG_CC}). Sometimes maintainers like to write an explicit link rule for their program. Without executable extension support, this is easy---you simply write a rule whose target is the name of the program. However, when executable extension support is enabled, you must instead add the @samp{$(EXEEXT)} suffix. Unfortunately, due to the change in Autoconf 2.50, this means you must always add this extension. However, this is a problem for maintainers who know their package will never run on a platform that has executable extensions. For those maintainers, the @code{no-exeext} option (@pxref{Options}) will disable this feature. This works in a fairly ugly way; if @code{no-exeext} is seen, then the presence of a rule for a target named @code{foo} in @file{Makefile.am} will override an automake-generated rule for @code{foo$(EXEEXT)}. Without the @code{no-exeext} option, this use will give a diagnostic. @node Other objects @chapter Other Derived Objects Automake can handle derived objects which are not C programs. Sometimes the support for actually building such objects must be explicitly supplied, but Automake will still automatically handle installation and distribution. @menu * Scripts:: Executable scripts * Headers:: Header files * Data:: Architecture-independent data files * Sources:: Derived sources @end menu @node Scripts @section Executable Scripts @cindex _SCRIPTS primary, defined @cindex SCRIPTS primary, defined @cindex Primary variable, SCRIPTS It is possible to define and install programs which are scripts. Such programs are listed using the @samp{SCRIPTS} primary name. Automake doesn't define any dependencies for scripts; the @file{Makefile.am} should include the appropriate rules. @vindex SCRIPTS Automake does not assume that scripts are derived objects; such objects must be deleted by hand (@pxref{Clean}). The @code{automake} program itself is a Perl script that is generated from @file{automake.in}. Here is how this is handled: @example bin_SCRIPTS = automake CLEANFILES = $(bin_SCRIPTS) do_subst = sed -e 's,[@@]datadir[@@],$(datadir),g' \ -e 's,[@@]PERL[@@],$(PERL),g' \ -e 's,[@@]PACKAGE[@@],$(PACKAGE),g' \ -e 's,[@@]VERSION[@@],$(VERSION),g' \ @dots{} automake: automake.in Makefile $(do_subst) < $(srcdir)/automake.in > automake chmod +x automake @end example Because---as we have just seen---scripts can be built, they are not distributed by default. Scripts that should be distributed can be specified using a @code{dist_} prefix as in other primaries. For instance the following @file{Makefile.am} declares that @file{my_script} should be distributed and installed in @code{$(sbindir)}. @example dist_sbin_SCRIPTS = my_script @end example @cindex SCRIPTS, installation directories @cindex Installing scripts @vindex bin_SCRIPTS @vindex sbin_SCRIPTS @vindex libexec_SCRIPTS @vindex pkgdata_SCRIPTS @vindex noinst_SCRIPTS @vindex check_SCRIPTS Script objects can be installed in @code{bindir}, @code{sbindir}, @code{libexecdir}, or @code{pkgdatadir}. Scripts that need not being installed can be listed in @code{noinst_SCRIPTS}, and among them, those which are needed only by @code{make check} should go in @code{check_SCRIPTS}. @node Headers @section Header files @cindex _HEADERS primary, defined @cindex HEADERS primary, defined @cindex Primary variable, HEADERS @vindex noinst_HEADERS @cindex HEADERS, installation directories @cindex Installing headers @vindex include_HEADERS @vindex oldinclude_HEADERS @vindex pkginclude_HEADERS Header files that must be installed are specified by the @samp{HEADERS} family of variables. Headers can be installed in @code{includedir}, @code{oldincludedir}, @code{pkgincludedir} or any other directory you may have defined (@pxref{Uniform}). For instance @example include_HEADERS = foo.h bar/bar.h @end example @noindent will install the two files as @file{$(includedir)/foo.h} and @file{$(includedir)/bar.h}. The @samp{nobase_} prefix is also supported, @example nobase_include_HEADERS = foo.h bar/bar.h @end example @noindent will install the two files as @file{$(includedir)/foo.h} and @file{$(includedir)/bar/bar.h} (@pxref{Alternative}). @vindex noinst_HEADERS Usually, only header files that accompany installed libraries need to be installed. Headers used by programs or convenience libraries are not installed. The @code{noinst_HEADERS} variable can be used for such headers. However when the header actually belongs to one convenient library or program, we recommend listing it in the program's or library's @samp{_SOURCES} variable (@pxref{Program Sources}) instead of in @code{noinst_HEADERS}. This is clearer for the @file{Makefile.am} reader. @code{noinst_HEADERS} would be the right variable to use in a directory containing only headers and no associated library or program. All header files must be listed somewhere; in a @samp{_SOURCES} variable or in a @samp{_HEADERS} variable. Missing ones will not appear in the distribution. For header files that are built and must not be distributed, use the @samp{nodist_} prefix as in @code{nodist_include_HEADERS} or @code{nodist_prog_SOURCES}. If these generated headers are needed during the build, you must also ensure they exist before they are used, see @xref{Sources}. @node Data @section Architecture-independent data files @cindex _DATA primary, defined @cindex DATA primary, defined @cindex Primary variable, DATA Automake supports the installation of miscellaneous data files using the @samp{DATA} family of variables. @vindex DATA @vindex data_DATA @vindex sysconf_DATA @vindex sharedstate_DATA @vindex localstate_DATA @vindex pkgdata_DATA Such data can be installed in the directories @code{datadir}, @code{sysconfdir}, @code{sharedstatedir}, @code{localstatedir}, or @code{pkgdatadir}. By default, data files are @emph{not} included in a distribution. Of course, you can use the @samp{dist_} prefix to change this on a per-variable basis. Here is how Automake declares its auxiliary data files: @example dist_pkgdata_DATA = clean-kr.am clean.am @dots{} @end example @node Sources @section Built sources Because Automake's automatic dependency tracking works as a side-effect of compilation (@pxref{Dependencies}) there is a bootstrap issue: a target should not be compiled before its dependencies are made, but these dependencies are unknown until the target is first compiled. Ordinarily this is not a problem, because dependencies are distributed sources: they preexist and do not need to be built. Suppose that @file{foo.c} includes @file{foo.h}. When it first compiles @file{foo.o}, @command{make} only knows that @file{foo.o} depends on @file{foo.c}. As a side-effect of this compilation @code{depcomp} records the @file{foo.h} dependency so that following invocations of @command{make} will honor it. In these conditions, it's clear there is no problem: either @file{foo.o} doesn't exist and has to be built (regardless of the dependencies), either accurate dependencies exist and they can be used to decide whether @file{foo.o} should be rebuilt. It's a different story if @file{foo.h} doesn't exist by the first @command{make} run. For instance there might be a rule to build @file{foo.h}. This time @file{file.o}'s build will fail because the compiler can't find @file{foo.h}. @command{make} failed to trigger the rule to build @file{foo.h} first by lack of dependency information. @vindex BUILT_SOURCES @cindex BUILT_SOURCES, defined The @code{BUILT_SOURCES} variable is a workaround for this problem. A source file listed in @code{BUILT_SOURCES} is made on @code{make all} or @code{make check} (or even @code{make install}) before other targets are processed. However, such a source file is not @emph{compiled} unless explicitly requested by mentioning it in some other @samp{_SOURCES} variable. So, to conclude our introductory example, we could use @code{BUILT_SOURCES = foo.h} to ensure @file{foo.h} gets built before any other target (including @file{foo.o}) during @code{make all} or @code{make check}. @code{BUILT_SOURCES} is actually a bit of a misnomer, as any file which must be created early in the build process can be listed in this variable. Moreover, all built sources do not necessarily have to be listed in @code{BUILT_SOURCES}. For instance a generated @file{.c} file doesn't need to appear in @code{BUILT_SOURCES} (unless it is included by another source), because it's a known dependency of the associated object. It might be important to emphasize that @code{BUILT_SOURCES} is honored only by @code{make all}, @code{make check} and @code{make install}. This means you cannot build a specific target (e.g., @code{make foo}) in a clean tree if it depends on a built source. However it will succeed if you have run @code{make all} earlier, because accurate dependencies are already available. The next section illustrates and discusses the handling of built sources on a toy example. @menu * Built sources example:: Several ways to handle built sources. @end menu @node Built sources example @subsection Built sources example Suppose that @file{foo.c} includes @file{bindir.h}, which is installation-dependent and not distributed: it needs to be built. Here @file{bindir.h} defines the preprocessor macro @code{bindir} to the value of the @command{make} variable @code{bindir} (inherited from @file{configure}). We suggest several implementations below. It's not meant to be an exhaustive listing of all ways to handle built sources, but it will give you a few ideas if you encounter this issue. @unnumberedsubsec First try This first implementation will illustrate the bootstrap issue mentioned in the previous section (@pxref{Sources}). Here is a tentative @file{Makefile.am}. @example # This won't work. bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@@ @end example This setup doesn't work, because Automake doesn't know that @file{foo.c} includes @file{bindir.h}. Remember, automatic dependency tracking works as a side-effect of compilation, so the dependencies of @file{foo.o} will be known only after @file{foo.o} has been compiled (@pxref{Dependencies}). The symptom is as follows. @example % make source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c foo.c:2: bindir.h: No such file or directory make: *** [foo.o] Error 1 @end example In this example @file{bindir.h} is not distributed, not installed, and it is not even being built on-time. One may wonder what the @code{nodist_foo_SOURCES = bindir.h} line has any use at all. This line simply states that @file{bindir.h} is a source of @code{foo}, so for instance it should be inspected while generating tags (@pxref{Tags}). In other words, it does not help our present problem, and the build would fail identically without it. @unnumberedsubsec Using @code{BUILT_SOURCES} A solution is to require @file{bindir.h} to be built before anything else. This is what @code{BUILT_SOURCES} is meant for (@pxref{Sources}). @example bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h BUILT_SOURCES = bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@@ @end example See how @file{bindir.h} get built first: @example % make echo '#define bindir "/usr/local/bin"' >bindir.h make all-am make[1]: Entering directory `/home/adl/tmp' source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c gcc -g -O2 -o foo foo.o make[1]: Leaving directory `/home/adl/tmp' @end example However, as said earlier, @code{BUILT_SOURCES} applies only to the @code{all}, @code{check}, and @code{install} targets. It still fails if you try to run @code{make foo} explicitly: @example % make clean test -z "bindir.h" || rm -f bindir.h test -z "foo" || rm -f foo rm -f *.o % : > .deps/foo.Po # Suppress previously recorded dependencies % make foo source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c foo.c:2: bindir.h: No such file or directory make: *** [foo.o] Error 1 @end example @unnumberedsubsec Recording dependencies manually Usually people are happy enough with @code{BUILT_SOURCES} because they never build targets such as @code{make foo} before @code{make all}, as in the previous example. However if this matters to you, you can avoid @code{BUILT_SOURCES} and record such dependencies explicitly in the @file{Makefile.am}. @example bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h foo.$(OBJEXT): bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@@ @end example You don't have to list @emph{all} the dependencies of @code{foo.o} explicitly, only those which might need to be built. If a dependency already exists, it will not hinder the first compilation and will be recorded by the normal dependency tracking code. (Note that after this first compilation the dependency tracking code will also have recorded the dependency between @code{foo.o} and @code{bindir.h}; so our explicit dependency is really useful to the first build only.) Adding explicit dependencies like this can be a bit dangerous if you are not careful enough. This is due to the way Automake tries not to overwrite your rules (it assumes you know better than it). @code{foo.$(OBJEXT): bindir.h} supersedes any rule Automake may want to output to build @code{foo.$(OBJEXT)}. It happens to work in this case because Automake doesn't have to output any @code{foo.$(OBJEXT):} target: it relies on a suffix rule instead (i.e., @code{.c.$(OBJEXT):}). Always check the generated @file{Makefile.in} if you do this. @unnumberedsubsec Build @file{bindir.h} from @file{configure} It's possible to define this preprocessor macro from @file{configure}, either in @file{config.h} (@pxref{Defining Directories, , Defining Directories, autoconf, The Autoconf Manual}), or by processing a @file{bindir.h.in} file using @code{AC_CONFIG_FILES} (@pxref{Configuration Actions, ,Configuration Actions, autoconf, The Autoconf Manual}). At this point it should be clear that building @file{bindir.h} from @file{configure} work well for this example. @file{bindir.h} will exist before you build any target, hence will not cause any dependency issue. The Makefile can be shrunk as follows. We do not even have to mention @file{bindir.h}. @example bin_PROGRAMS = foo foo_SOURCES = foo.c @end example However, it's not always possible to build sources from @file{configure}, especially when these sources are generated by a tool that needs to be built first... @unnumberedsubsec Build @file{bindir.c}, not @file{bindir.h}. Another attractive idea is to define @code{bindir} as a variable or function exported from @file{bindir.o}, and build @file{bindir.c} instead of @file{bindir.h}. @example noinst_PROGRAMS = foo foo_SOURCES = foo.c bindir.h nodist_foo_SOURCES = bindir.c CLEANFILES = bindir.c bindir.c: Makefile echo 'const char bindir[] = "$(bindir)";' >$@ @end example @file{bindir.h} contains just the variable's declaration and doesn't need to be built, so it won't cause any trouble. @file{bindir.o} is always dependent on @file{bindir.c}, so @file{bindir.c} will get built first. @unnumberedsubsec Which is best? There is no panacea, of course. Each solution has its merits and drawbacks. You cannot use @code{BUILT_SOURCES} if the ability to run @code{make foo} on a clean tree is important to you. You won't add explicit dependencies if you are leery of overriding an Automake rule by mistake. Building files from @file{./configure} is not always possible, neither is converting @file{.h} files into @file{.c} files. @node Other GNU Tools @chapter Other GNU Tools Since Automake is primarily intended to generate @file{Makefile.in}s for use in GNU programs, it tries hard to interoperate with other GNU tools. @menu * Emacs Lisp:: Emacs Lisp * gettext:: Gettext * Libtool:: Libtool * Java:: Java * Python:: Python @end menu @node Emacs Lisp @section Emacs Lisp @cindex _LISP primary, defined @cindex LISP primary, defined @cindex Primary variable, LISP @vindex LISP @vindex lisp_LISP @vindex noinst_LISP Automake provides some support for Emacs Lisp. The @samp{LISP} primary is used to hold a list of @file{.el} files. Possible prefixes for this primary are @samp{lisp_} and @samp{noinst_}. Note that if @code{lisp_LISP} is defined, then @file{configure.ac} must run @code{AM_PATH_LISPDIR} (@pxref{Macros}). Automake will byte-compile all Emacs Lisp source files using the Emacs found by @code{AM_PATH_LISPDIR}, if any was found. Byte-compiled Emacs Lisp files are not portable among all versions of Emacs, so it makes sense to turn this off if you expect sites to have more than one version of Emacs installed. Furthermore, many packages don't actually benefit from byte-compilation. Still, we recommend that you byte-compile your Emacs Lisp sources. It is probably better for sites with strange setups to cope for themselves than to make the installation less nice for everybody else. There are two ways to avoid byte-compiling. Historically, we have recommended the following construct. @example lisp_LISP = file1.el file2.el ELCFILES = @end example @noindent @code{ELCFILES} is an internal Automake variable that normally lists all @file{.elc} files that must be byte-compiled. Automake defines @code{ELCFILES} automatically from @code{lisp_LISP}. Emptying this variable explicitly prevents byte-compilation to occur. Since Automake 1.8, we now recommend using @code{lisp_DATA} instead. As in @example lisp_DATA = file1.el file2.el @end example Note that these two constructs are not equivalent. @code{_LISP} will not install a file if Emacs is not installed, while @code{_DATA} will always install its files. @node gettext @section Gettext @cindex GNU Gettext support @cindex Gettext support @cindex Support for GNU Gettext If @code{AM_GNU_GETTEXT} is seen in @file{configure.ac}, then Automake turns on support for GNU gettext, a message catalog system for internationalization (@pxref{GNU Gettext, , , gettext, GNU gettext utilities}). The @code{gettext} support in Automake requires the addition of two subdirectories to the package, @file{intl} and @file{po}. Automake insures that these directories exist and are mentioned in @code{SUBDIRS}. @vindex dist_lisp_LISP @vindex dist_noinst_LISP Lisp sources are not distributed by default. You can prefix the @code{LISP} primary with @code{dist_}, as in @code{dist_lisp_LISP} or @code{dist_noinst_LISP}, to indicate that these files should be distributed. @node Libtool @section Libtool Automake provides support for GNU Libtool (@pxref{Top, , Introduction, libtool, The Libtool Manual}) with the @samp{LTLIBRARIES} primary. @xref{A Shared Library}. @node Java @section Java @cindex _JAVA primary, defined @cindex JAVA primary, defined @cindex Primary variable, JAVA Automake provides some minimal support for Java compilation with the @samp{JAVA} primary. Any @file{.java} files listed in a @samp{_JAVA} variable will be compiled with @code{JAVAC} at build time. By default, @file{.class} files are not included in the distribution. @cindex JAVA restrictions @cindex Restrictions for JAVA Currently Automake enforces the restriction that only one @samp{_JAVA} primary can be used in a given @file{Makefile.am}. The reason for this restriction is that, in general, it isn't possible to know which @file{.class} files were generated from which @file{.java} files -- so it would be impossible to know which files to install where. For instance, a @file{.java} file can define multiple classes; the resulting @file{.class} file names cannot be predicted without parsing the @file{.java} file. There are a few variables which are used when compiling Java sources: @vtable @code @item JAVAC The name of the Java compiler. This defaults to @samp{javac}. @item JAVACFLAGS The flags to pass to the compiler. This is considered to be a user variable (@pxref{User Variables}). @item AM_JAVACFLAGS More flags to pass to the Java compiler. This, and not @code{JAVACFLAGS}, should be used when it is necessary to put Java compiler flags into @file{Makefile.am}. @item JAVAROOT The value of this variable is passed to the @samp{-d} option to @code{javac}. It defaults to @samp{$(top_builddir)}. @item CLASSPATH_ENV This variable is an @code{sh} expression which is used to set the @code{CLASSPATH} environment variable on the @code{javac} command line. (In the future we will probably handle class path setting differently.) @end vtable @node Python @section Python @cindex _PYTHON primary, defined @cindex PYTHON primary, defined @cindex Primary variable, PYTHON Automake provides support for Python compilation with the @samp{PYTHON} primary. Any files listed in a @samp{_PYTHON} variable will be byte-compiled with @code{py-compile} at install time. @code{py-compile} actually creates both standard (@file{.pyc}) and byte-compiled (@file{.pyo}) versions of the source files. Note that because byte-compilation occurs at install time, any files listed in @samp{noinst_PYTHON} will not be compiled. Python source files are included in the distribution by default. Automake ships with an Autoconf macro called @code{AM_PATH_PYTHON} which will determine some Python-related directory variables (see below). If you have called @code{AM_PATH_PYTHON} from @file{configure.ac}, then you may use the following variables to list you Python source files in your variables: @samp{python_PYTHON}, @samp{pkgpython_PYTHON}, @samp{pyexecdir_PYTHON}, @samp{pkgpyexecdir_PYTHON}, depending where you want your files installed. @code{AM_PATH_PYTHON([@var{VERSION}], [@var{ACTION-IF-FOUND}], [@var{ACTION-IF-NOT-FOUND}])} takes three optional arguments. It will search a Python interpreter on the system. The first argument, if present, is the minimum version of Python required for this package: @code{AM_PATH_PYTHON} will skip any Python interpreter which is older than @var{VERSION}. If an interpreter is found and satisfies @var{VERSION}, then @var{ACTION-IF-FOUND} is run. Otherwise, @var{ACTION-IF-NOT-FOUND} is run. If @var{ACTION-IF-NOT-FOUND} is not specified, the default is to abort configure. This is fine when Python is an absolute requirement for the package. Therefore if Python >= 2.2 is only @emph{optional} to the package, @code{AM_PATH_PYTHON} could be called as follows. @example AM_PATH_PYTHON(2.2,, :) @end example @code{AM_PATH_PYTHON} creates several output variables based on the Python installation found during configuration. @vtable @code @item PYTHON The name of the Python executable, or @code{:} if no suitable interpreter could be found. Assuming @var{ACTION-IF-NOT-FOUND} is used (otherwise @file{./configure} will abort if Python is absent), the value of @code{PYTHON} can be used to setup a conditional in order to disable the relevant part of a build as follows. @example AM_PATH_PYTHON(,, :) AM_CONDITIONAL([HAVE_PYTHON], [test "$PYTHON" != :]) @end example If the @var{ACTION-IF-NOT-FOUND} is specified @item PYTHON_VERSION The Python version number, in the form @var{major}.@var{minor} (e.g. @samp{1.5}). This is currently the value of @code{sys.version[:3]}. @item PYTHON_PREFIX The string @code{$@{prefix@}}. This term may be used in future work which needs the contents of Python's @code{sys.prefix}, but general consensus is to always use the value from configure. @item PYTHON_EXEC_PREFIX The string @code{$@{exec_prefix@}}. This term may be used in future work which needs the contents of Python's @code{sys.exec_prefix}, but general consensus is to always use the value from configure. @item PYTHON_PLATFORM The canonical name used by Python to describe the operating system, as given by @code{sys.platform}. This value is sometimes needed when building Python extensions. @item pythondir The directory name for the @file{site-packages} subdirectory of the standard Python install tree. @item pkgpythondir This is is the directory under @code{pythondir} which is named after the package. That is, it is @samp{$(pythondir)/$(PACKAGE)}. It is provided as a convenience. @item pyexecdir This is the directory where Python extension modules (shared libraries) should be installed. @item pkgpyexecdir This is a convenience variable which is defined as @samp{$(pyexecdir)/$(PACKAGE)}. @end vtable All these directory variables have values that start with either @code{$@{prefix@}} or @code{$@{exec_prefix@}} unexpanded. This works fine in @file{Makefiles}, but it makes these variables hard to use in @file{configure}. This is mandated by the GNU coding standards, so that the user can run @code{make prefix=/foo install}. The Autoconf manual has a section with more details on this topic (@pxref{Installation Directory Variables, , Installation Directory Variables, autoconf, The Autoconf Manual}). @node Documentation @chapter Building documentation Currently Automake provides support for Texinfo and man pages. @menu * Texinfo:: Texinfo * Man pages:: Man pages @end menu @node Texinfo @section Texinfo @cindex _TEXINFOS primary, defined @cindex TEXINFOS primary, defined @cindex Primary variable, TEXINFOS @cindex HTML output using Texinfo @cindex PDF output using Texinfo @cindex PS output using Texinfo @cindex DVI output using Texinfo If the current directory contains Texinfo source, you must declare it with the @samp{TEXINFOS} primary. Generally Texinfo files are converted into info, and thus the @code{info_TEXINFOS} variable is most commonly used here. Any Texinfo source file must end in the @file{.texi}, @file{.txi}, or @file{.texinfo} extension. We recommend @file{.texi} for new manuals. @vindex TEXINFOS @vindex info_TEXINFOS Automake generates rules to build @file{.info}, @file{.dvi}, @file{.ps}, @file{.pdf} and @file{.html} files from your Texinfo sources. The @file{.info} files are built by @code{make all} and installed by @code{make install} (unless you use @code{no-installinfo}, see below). The other files can be built on request by @code{make dvi}, @code{make ps}, @code{make pdf} and @code{make html}. @cindex Texinfo flag, VERSION @cindex Texinfo flag, UPDATED @cindex Texinfo flag, EDITION @cindex Texinfo flag, UPDATED-MONTH @cindex VERSION Texinfo flag @cindex UPDATED Texinfo flag @cindex EDITION Texinfo flag @cindex UPDATED-MONTH Texinfo flag @cindex mdate-sh If the @file{.texi} file @code{@@include}s @file{version.texi}, then that file will be automatically generated. The file @file{version.texi} defines four Texinfo flag you can reference using @code{@@value@{EDITION@}}, @code{@@value@{VERSION@}}, @code{@@value@{UPDATED@}}, and @code{@@value@{UPDATED-MONTH@}}. @table @code @item EDITION @itemx VERSION Both of these flags hold the version number of your program. They are kept separate for clarity. @item UPDATED This holds the date the primary @file{.texi} file was last modified. @item UPDATED-MONTH This holds the name of the month in which the primary @file{.texi} file was last modified. @end table The @file{version.texi} support requires the @code{mdate-sh} program; this program is supplied with Automake and automatically included when @code{automake} is invoked with the @code{--add-missing} option. If you have multiple Texinfo files, and you want to use the @file{version.texi} feature, then you have to have a separate version file for each Texinfo file. Automake will treat any include in a Texinfo file that matches @samp{vers*.texi} just as an automatically generated version file. Sometimes an info file actually depends on more than one @file{.texi} file. For instance, in GNU Hello, @file{hello.texi} includes the file @file{gpl.texi}. You can tell Automake about these dependencies using the @code{@var{texi}_TEXINFOS} variable. Here is how GNU Hello does it: @vindex TEXINFOS @vindex _TEXINFOS @example info_TEXINFOS = hello.texi hello_TEXINFOS = gpl.texi @end example @cindex texinfo.tex By default, Automake requires the file @file{texinfo.tex} to appear in the same directory as the Texinfo source (this can be changed using the @code{TEXINFO_TEX} variable, see below). However, if you used @code{AC_CONFIG_AUX_DIR} in @file{configure.ac} (@pxref{Input, , Finding `configure' Input, autoconf, The Autoconf Manual}), then @file{texinfo.tex} is looked for there. Automake supplies @file{texinfo.tex} if @samp{--add-missing} is given. @opindex no-texinfo.tex The option @samp{no-texinfo.tex} can be used to eliminate the requirement for @file{texinfo.tex}. Use of the variable @code{TEXINFO_TEX} is preferable, however, because that allows the @code{dvi}, @code{ps}, and @code{pdf} targets to still work. @cindex Rule, install-info @cindex Rule, noinstall-info @cindex Target, install-info @cindex Target, noinstall-info @cindex install-info target @cindex noinstall-info target @opindex no-installinfo @trindex install-info Automake generates an @code{install-info} rule; some people apparently use this. By default, info pages are installed by @samp{make install}. This can be prevented via the @code{no-installinfo} option. The following variables are used by the Texinfo build rules. @vtable @code @item MAKEINFO The name of the program invoked to build @file{.info} files. This variable is defined by Automake. If the @code{makeinfo} program is found on the system then it will be used by default; otherwise @code{missing} will be used instead. @item MAKEINFOHTML The command invoked to build @file{.html} files. Automake defines this to @code{$(MAKEINFO) --html}. @item MAKEINFOFLAGS User flags passed to each invocation of @code{$(MAKEINFO)} and @code{$(MAKEINFOHTML)}. This user variable (@pxref{User Variables}) is not expected to be defined in any @file{Makefile}; it can be used by users to pass extra flags to suit their needs. @item AM_MAKEINFOFLAGS @itemx AM_MAKEINFOHTMLFLAGS Maintainer flags passed to each @code{makeinfo} invocation. These are maintainer variables that can be overridden in @file{Makefile.am}. @code{$(AM_MAKEINFOFLAGS)} is passed to @code{makeinfo} when building @file{.info} files; and @code{$(AM_MAKEINFOHTMLFLAGS)} is used when building @file{.html} files. For instance the following setting can be used to obtain one single @file{.html} file per manual, without node separators. @example AM_MAKEINFOHTMLFLAGS = --no-headers --no-split @end example By default, @code{$(AM_MAKEINFOHTMLFLAGS)} is set to @code{$(AM_MAKEINFOFLAGS)}. This means that defining @code{$(AM_MAKEINFOFLAGS)} without defining @code{$(AM_MAKEINFOHTMLFLAGS)} will impact builds of both @file{.info} and @file{.html} files. @item TEXI2DVI The name of the command that converts a @file{.texi} file into a @file{.dvi} file. This defaults to @code{texi2dvi}, a script that ships with the Texinfo package. @item TEXI2PDF The name of the command that translates a @file{.texi} file into a @file{.pdf} file. This defaults to @code{$(TEXI2DVI) --pdf --batch}. @item DVIPS The name of the command that build a @file{.ps} file out of a @file{.dvi} file. This defaults to @code{dvips}. @item TEXINFO_TEX If your package has Texinfo files in many directories, you can use the variable @code{TEXINFO_TEX} to tell Automake where to find the canonical @file{texinfo.tex} for your package. The value of this variable should be the relative path from the current @file{Makefile.am} to @file{texinfo.tex}: @example TEXINFO_TEX = ../doc/texinfo.tex @end example @end vtable @node Man pages @section Man pages @cindex _MANS primary, defined @cindex MANS primary, defined @cindex Primary variable, MANS A package can also include man pages (but see the GNU standards on this matter, @ref{Man Pages, , , standards, The GNU Coding Standards}.) Man pages are declared using the @samp{MANS} primary. Generally the @code{man_MANS} variable is used. Man pages are automatically installed in the correct subdirectory of @code{mandir}, based on the file extension. @vindex MANS @vindex man_MANS File extensions such as @samp{.1c} are handled by looking for the valid part of the extension and using that to determine the correct subdirectory of @code{mandir}. Valid section names are the digits @samp{0} through @samp{9}, and the letters @samp{l} and @samp{n}. Sometimes developers prefer to name a man page something like @file{foo.man} in the source, and then rename it to have the correct suffix, e.g. @file{foo.1}, when installing the file. Automake also supports this mode. For a valid section named @var{SECTION}, there is a corresponding directory named @samp{man@var{SECTION}dir}, and a corresponding @samp{_MANS} variable. Files listed in such a variable are installed in the indicated section. If the file already has a valid suffix, then it is installed as-is; otherwise the file suffix is changed to match the section. For instance, consider this example: @example man1_MANS = rename.man thesame.1 alsothesame.1c @end example In this case, @file{rename.man} will be renamed to @file{rename.1} when installed, but the other files will keep their names. @cindex Rule, install-man @cindex Rule, noinstall-man @cindex Target, install-man @cindex Target, noinstall-man @cindex install-man target @cindex noinstall-man target @c Use @samp{make install} per documentation: (texi)code. By default, man pages are installed by @samp{make install}. However, since the GNU project does not require man pages, many maintainers do not expend effort to keep the man pages up to date. In these cases, the @code{no-installman} option will prevent the man pages from being installed by default. The user can still explicitly install them via @samp{make install-man}. @opindex no-installman @trindex install-man Here is how the man pages are handled in GNU @code{cpio} (which includes both Texinfo documentation and man pages): @example man_MANS = cpio.1 mt.1 EXTRA_DIST = $(man_MANS) @end example Man pages are not currently considered to be source, because it is not uncommon for man pages to be automatically generated. Therefore they are not automatically included in the distribution. However, this can be changed by use of the @samp{dist_} prefix. The @samp{nobase_} prefix is meaningless for man pages and is disallowed. @node Install @chapter What Gets Installed @cindex Installation support @cindex make install support @section Basics of installation Naturally, Automake handles the details of actually installing your program once it has been built. All files named by the various primaries are automatically installed in the appropriate places when the user runs @code{make install}. A file named in a primary is installed by copying the built file into the appropriate directory. The base name of the file is used when installing. @example bin_PROGRAMS = hello subdir/goodbye @end example In this example, both @samp{hello} and @samp{goodbye} will be installed in @code{$(bindir)}. Sometimes it is useful to avoid the basename step at install time. For instance, you might have a number of header files in subdirectories of the source tree which are laid out precisely how you want to install them. In this situation you can use the @samp{nobase_} prefix to suppress the base name step. For example: @example nobase_include_HEADERS = stdio.h sys/types.h @end example Will install @file{stdio.h} in @code{$(includedir)} and @file{types.h} in @code{$(includedir)/sys}. @section The two parts of install Automake generates separate @code{install-data} and @code{install-exec} rules, in case the installer is installing on multiple machines which share directory structure---these targets allow the machine-independent parts to be installed only once. @code{install-exec} installs platform-dependent files, and @code{install-data} installs platform-independent files. The @code{install} target depends on both of these targets. While Automake tries to automatically segregate objects into the correct category, the @file{Makefile.am} author is, in the end, responsible for making sure this is done correctly. @trindex install-data @trindex install-exec @trindex install @cindex Install, two parts of Variables using the standard directory prefixes @samp{data}, @samp{info}, @samp{man}, @samp{include}, @samp{oldinclude}, @samp{pkgdata}, or @samp{pkginclude} (e.g. @samp{data_DATA}) are installed by @samp{install-data}. Variables using the standard directory prefixes @samp{bin}, @samp{sbin}, @samp{libexec}, @samp{sysconf}, @samp{localstate}, @samp{lib}, or @samp{pkglib} (e.g. @samp{bin_PROGRAMS}) are installed by @samp{install-exec}. Any variable using a user-defined directory prefix with @samp{exec} in the name (e.g. @samp{myexecbin_PROGRAMS} is installed by @samp{install-exec}. All other user-defined prefixes are installed by @samp{install-data}. @section Extending installation It is possible to extend this mechanism by defining an @code{install-exec-local} or @code{install-data-local} rule. If these rules exist, they will be run at @samp{make install} time. These rules can do almost anything; care is required. @trindex install-exec-local @trindex install-data-local Automake also supports two install hooks, @code{install-exec-hook} and @code{install-data-hook}. These hooks are run after all other install rules of the appropriate type, exec or data, have completed. So, for instance, it is possible to perform post-installation modifications using an install hook. @cindex Install hook @section Staged installs @vindex DESTDIR Automake generates support for the @samp{DESTDIR} variable in all install rules. @samp{DESTDIR} is used during the @samp{make install} step to relocate install objects into a staging area. Each object and path is prefixed with the value of @samp{DESTDIR} before being copied into the install area. Here is an example of typical DESTDIR usage: @example mkdir /tmp/staging && make DESTDIR=/tmp/staging install @end example The @command{mkdir} command avoids a security problem if the attacker creates a symbolic link from @file{/tmp/staging} to a victim area; then @command{make} places install objects in a directory tree built under @file{/tmp/staging}. If @file{/gnu/bin/foo} and @file{/gnu/share/aclocal/foo.m4} are to be installed, the above command would install @file{/tmp/staging/gnu/bin/foo} and @file{/tmp/staging/gnu/share/aclocal/foo.m4}. This feature is commonly used to build install images and packages. For more information, see @ref{Makefile Conventions, , , standards, The GNU Coding Standards}. Support for @samp{DESTDIR} is implemented by coding it directly into the install rules. If your @file{Makefile.am} uses a local install rule (e.g., @code{install-exec-local}) or an install hook, then you must write that code to respect @samp{DESTDIR}. @section Rules for the user Automake also generates rules for targets @code{uninstall}, @code{installdirs}, and @code{install-strip}. @trindex uninstall @trindex installdirs @trindex install-strip Automake supports @code{uninstall-local} and @code{uninstall-hook}. There is no notion of separate uninstalls for ``exec'' and ``data'', as these features would not provide additional functionality. Note that @code{uninstall} is not meant as a replacement for a real packaging tool. @node Clean @chapter What Gets Cleaned @cindex make clean support The GNU Makefile Standards specify a number of different clean rules. See @xref{Standard Targets, , Standard Targets for Users, standards, The GNU Coding Standards}. Generally the files that can be cleaned are determined automatically by Automake. Of course, Automake also recognizes some variables that can be defined to specify additional files to clean. These variables are @code{MOSTLYCLEANFILES}, @code{CLEANFILES}, @code{DISTCLEANFILES}, and @code{MAINTAINERCLEANFILES}. @vindex MOSTLYCLEANFILES @vindex CLEANFILES @vindex DISTCLEANFILES @vindex MAINTAINERCLEANFILES As the GNU Standards aren't always explicit as to which files should be removed by which rule, we've adopted a heuristic which we believe was first formulated by Fran@,{c}ois Pinard: @itemize @bullet @item If @code{make} built it, and it is commonly something that one would want to rebuild (for instance, a @file{.o} file), then @code{mostlyclean} should delete it. @item Otherwise, if @code{make} built it, then @code{clean} should delete it. @item If @code{configure} built it, then @code{distclean} should delete it. @item If the maintainer built it (for instance, a @file{.info} file), then @code{maintainer-clean} should delete it. However @code{maintainer-clean} should not delete anything that needs to exist in order to run @code{./configure && make}. @end itemize We recommend that you follow this same set of heuristics in your @file{Makefile.am}. @node Dist @chapter What Goes in a Distribution @section Basics of distribution @cindex make dist The @code{dist} rule in the generated @file{Makefile.in} can be used to generate a gzip'd @code{tar} file and other flavors of archive for distribution. The files is named based on the @samp{PACKAGE} and @samp{VERSION} variables defined by @code{AM_INIT_AUTOMAKE} (@pxref{Macros}); more precisely the gzip'd @code{tar} file is named @samp{@var{package}-@var{version}.tar.gz}. @cvindex PACKAGE @cvindex VERSION @trindex dist You can use the @code{make} variable @samp{GZIP_ENV} to control how gzip is run. The default setting is @samp{--best}. For the most part, the files to distribute are automatically found by Automake: all source files are automatically included in a distribution, as are all @file{Makefile.am}s and @file{Makefile.in}s. Automake also has a built-in list of commonly used files which are automatically included if they are found in the current directory (either physically, or as the target of a @file{Makefile.am} rule). This list is printed by @samp{automake --help}. Also, files which are read by @code{configure} (i.e. the source files corresponding to the files specified in various Autoconf macros such as @code{AC_CONFIG_FILES} and siblings) are automatically distributed. Files included in @file{Makefile.am}s (using @code{include}) or in @file{configure.ac} (using @code{m4_include}), and helper scripts installed with @samp{automake --add-missing} are also distributed. @cvindex m4_include, distribution Still, sometimes there are files which must be distributed, but which are not covered in the automatic rules. These files should be listed in the @code{EXTRA_DIST} variable. You can mention files from subdirectories in @code{EXTRA_DIST}. You can also mention a directory in @code{EXTRA_DIST}; in this case the entire directory will be recursively copied into the distribution. Please note that this will also copy @emph{everything} in the directory, including CVS/RCS version control files. We recommend against using this feature. @vindex EXTRA_DIST If you define @code{SUBDIRS}, Automake will recursively include the subdirectories in the distribution. If @code{SUBDIRS} is defined conditionally (@pxref{Conditionals}), Automake will normally include all directories that could possibly appear in @code{SUBDIRS} in the distribution. If you need to specify the set of directories conditionally, you can set the variable @code{DIST_SUBDIRS} to the exact list of subdirectories to include in the distribution (@pxref{Conditional Subdirectories}). @vindex DIST_SUBDIRS @section Fine-grained distribution control Sometimes you need tighter control over what does @emph{not} go into the distribution; for instance you might have source files which are generated and which you do not want to distribute. In this case Automake gives fine-grained control using the @samp{dist} and @samp{nodist} prefixes. Any primary or @samp{_SOURCES} variable can be prefixed with @samp{dist_} to add the listed files to the distribution. Similarly, @samp{nodist_} can be used to omit the files from the distribution. @vindex dist_ @vindex nodist_ As an example, here is how you would cause some data to be distributed while leaving some source code out of the distribution: @example dist_data_DATA = distribute-this bin_PROGRAMS = foo nodist_foo_SOURCES = do-not-distribute.c @end example @section The dist hook @trindex dist-hook Occasionally it is useful to be able to change the distribution before it is packaged up. If the @code{dist-hook} rule exists, it is run after the distribution directory is filled, but before the actual tar (or shar) file is created. One way to use this is for distributing files in subdirectories for which a new @file{Makefile.am} is overkill: @example dist-hook: mkdir $(distdir)/random cp -p $(srcdir)/random/a1 $(srcdir)/random/a2 $(distdir)/random @end example Another way to to use this is for removing unnecessary files that get recursively included by specifying a directory in EXTRA_DIST: @example EXTRA_DIST = doc dist-hook: rm -rf `find $(distdir)/doc -name CVS` @end example @vindex distdir @vindex top_distdir Two variables that come handy when writing @code{dist-hook} rules are @code{$(distdir)} and @code{$(top_distdir)}. @code{$(distdir)} points to the directory where the @code{dist} rule will copy files from the current directory before creating the tarball. If you are at the top-level directory, then @code{distdir = $(PACKAGE)-$(VERSION)}. When used from subdirectory named @file{foo/}, then @code{distdir = ../$(PACKAGE)-$(VERSION)/foo}. @code{$(distdir)} can be a relative or absolute path, do not assume any form. @code{$(top_distdir)} always points to the root directory of the distributed tree. At the top-level it's equal to @code{$(distdir)}. In the @file{foo/} subdirectory @code{top_distdir = ../$(PACKAGE)-$(VERSION)}. @code{$(top_distdir)} too can be a relative or absolute path. Note that when packages are nested using @code{AC_CONFIG_SUBDIRS} (@pxref{Subpackages}), then @code{$(distdir)} and @code{$(top_distdir)} are relative to the package where @code{make dist} was run, not to any sub-packages involved. @section Checking the distribution @cindex make distcheck @cindex make distcleancheck @vindex distcleancheck_listfiles @cindex make distuninstallcheck @vindex distuninstallcheck_listfiles Automake also generates a @code{distcheck} rule which can be of help to ensure that a given distribution will actually work. @code{distcheck} makes a distribution, then tries to do a @code{VPATH} build, run the test suite, and finally make another tarfile to ensure the distribution is self-contained. @trindex distcheck Building the package involves running @code{./configure}. If you need to supply additional flags to @code{configure}, define them in the @code{DISTCHECK_CONFIGURE_FLAGS} variable, either in your top-level @file{Makefile.am}, or on the command line when invoking @code{make}. @vindex DISTCHECK_CONFIGURE_FLAGS If the @code{distcheck-hook} rule is defined in your top-level @file{Makefile.am}, then it will be invoked by @code{distcheck} after the new distribution has been unpacked, but before the unpacked copy is configured and built. Your @code{distcheck-hook} can do almost anything, though as always caution is advised. Generally this hook is used to check for potential distribution errors not caught by the standard mechanism. Note that @code{distcheck-hook} as well as @code{DISTCHECK_CONFIGURE_FLAGS} are not honored in a subpackage @file{Makefile.am}, but the @code{DISTCHECK_CONFIGURE_FLAGS} are passed down to the @code{configure} script of the subpackage. Speaking about potential distribution errors, @code{distcheck} will also ensure that the @code{distclean} rule actually removes all built files. This is done by running @code{make distcleancheck} at the end of the @code{VPATH} build. By default, @code{distcleancheck} will run @code{distclean} and then make sure the build tree has been emptied by running @code{$(distcleancheck_listfiles)}. Usually this check will find generated files that you forgot to add to the @code{DISTCLEANFILES} variable (@pxref{Clean}). @trindex distcleancheck The @code{distcleancheck} behavior should be OK for most packages, otherwise you have the possibility to override the definition of either the @code{distcleancheck} rule, or the @code{$(distcleancheck_listfiles)} variable. For instance to disable @code{distcleancheck} completely, add the following rule to your top-level @file{Makefile.am}: @vindex distcleancheck_listfiles @example distcleancheck: @@: @end example If you want @code{distcleancheck} to ignore built files which have not been cleaned because they are also part of the distribution, add the following definition instead: @example distcleancheck_listfiles = \ find -type f -exec sh -c 'test -f $(srcdir)/@{@} || echo @{@}' ';' @end example The above definition is not the default because it's usually an error if your Makefiles cause some distributed files to be rebuilt when the user build the package. (Think about the user missing the tool required to build the file; or if the required tool is built by your package, consider the cross-compilation case where it can't be run.) There is a FAQ entry about this (@pxref{distcleancheck}), make sure you read it before playing with @code{distcleancheck_listfiles}. @code{distcheck} also checks that the @code{uninstall} rule works properly, both for ordinary and @samp{DESTDIR} builds. It does this by invoking @code{make uninstall}, and then it checks the install tree to see if any files are left over. This check will make sure that you correctly coded your @code{uninstall}-related rules. By default, the checking is done by the @code{distuninstallcheck} rule, and the list of files in the install tree is generated by @code{$(distuninstallcheck_listfiles}) (this is a variable whose value is a shell command to run that prints the list of files to stdout). Either of these can be overridden to modify the behavior of @code{distcheck}. For instance, to disable this check completely, you would write: @example distuninstallcheck: @@: @end example @section The types of distributions Automake generates rules to provide archives of the project for distributions in various formats. Their targets are: @table @asis @item @code{dist-bzip2} Generate a bzip2 tar archive of the distribution. bzip2 archives are frequently smaller than gzipped archives. @trindex dist-bzip2 @item @code{dist-gzip} Generate a gzip tar archive of the distribution. @trindex dist-gzip @item @code{dist-shar} Generate a shar archive of the distribution. @trindex dist-shar @item @code{dist-zip} Generate a zip archive of the distribution. @trindex dist-zip @item @code{dist-tarZ} Generate a compressed tar archive of the distribution. @trindex dist-tarZ @end table The rule @code{dist} (and its historical synonym @code{dist-all}) will create archives in all the enabled formats, @ref{Options}. By default, only the @code{dist-gzip} target is hooked to @code{dist}. @node Tests @chapter Support for test suites @cindex Test suites @cindex make check Automake supports two forms of test suites. @section Simple Tests If the variable @code{TESTS} is defined, its value is taken to be a list of programs to run in order to do the testing. The programs can either be derived objects or source objects; the generated rule will look both in @code{srcdir} and @file{.}. Programs needing data files should look for them in @code{srcdir} (which is both an environment variable and a make variable) so they work when building in a separate directory (@pxref{Build Directories, , Build Directories , autoconf, The Autoconf Manual}), and in particular for the @code{distcheck} rule (@pxref{Dist}). @cindex Exit status 77, special interpretation The number of failures will be printed at the end of the run. If a given test program exits with a status of 77, then its result is ignored in the final count. This feature allows non-portable tests to be ignored in environments where they don't make sense. The variable @code{TESTS_ENVIRONMENT} can be used to set environment variables for the test run; the environment variable @code{srcdir} is set in the rule. If all your test programs are scripts, you can also set @code{TESTS_ENVIRONMENT} to an invocation of the shell (e.g. @samp{$(SHELL) -x}); this can be useful for debugging the tests. @vindex TESTS @vindex TESTS_ENVIRONMENT @cindex Tests, expected failure @cindex Expected test failure You may define the variable @code{XFAIL_TESTS} to a list of tests (usually a subset of @code{TESTS}) that are expected to fail. This will reverse the result of those tests. @vindex XFAIL_TESTS Automake ensures that each program listed in @code{TESTS} is built before any tests are run; you can list both source and derived programs in @code{TESTS}. For instance, you might want to run a C program as a test. To do this you would list its name in @code{TESTS} and also in @code{check_PROGRAMS}, and then specify it as you would any other program. @section DejaGnu Tests If @uref{ftp://ftp.gnu.org/gnu/dejagnu/, @samp{dejagnu}} appears in @code{AUTOMAKE_OPTIONS}, then a @code{dejagnu}-based test suite is assumed. The variable @code{DEJATOOL} is a list of names which are passed, one at a time, as the @code{--tool} argument to @code{runtest} invocations; it defaults to the name of the package. The variable @code{RUNTESTDEFAULTFLAGS} holds the @code{--tool} and @code{--srcdir} flags that are passed to dejagnu by default; this can be overridden if necessary. @vindex RUNTESTDEFAULTFLAGS The variables @code{EXPECT} and @code{RUNTEST} can also be overridden to provide project-specific values. For instance, you will need to do this if you are testing a compiler toolchain, because the default values do not take into account host and target names. @opindex dejagnu @vindex DEJATOOL @vindex EXPECT @vindex RUNTEST The contents of the variable @code{RUNTESTFLAGS} are passed to the @code{runtest} invocation. This is considered a ``user variable'' (@pxref{User Variables}). If you need to set @code{runtest} flags in @file{Makefile.am}, you can use @code{AM_RUNTESTFLAGS} instead. @vindex RUNTESTFLAGS @vindex AM_RUNTESTFLAGS @cindex @file{site.exp} Automake will generate rules to create a local @file{site.exp} file, defining various variables detected by @code{./configure}. This file is automatically read by DejaGnu. It is OK for the user of a package to edit this file in order to tune the test suite. However this is not the place where the test suite author should define new variables: this should be done elsewhere in the real test suite code. Especially, @file{site.exp} should not be distributed. For more information regarding DejaGnu test suites, see @xref{Top, , , dejagnu, The DejaGnu Manual}. In either case, the testing is done via @samp{make check}. @section Install Tests The @code{installcheck} target is available to the user as a way to run any tests after the package has been installed. You can add tests to this by writing an @code{installcheck-local} rule. @node Rebuilding @chapter Rebuilding Makefiles @cindex rebuild rules Automake generates rules to automatically rebuild @file{Makefile}s, @file{configure}, and other derived files like @file{Makefile.in}. @cvindex AM_MAINTAINER_MODE If you are using @code{AM_MAINTAINER_MODE} in @file{configure.ac}, then these automatic rebuilding rules are only enabled in maintainer mode. @vindex ACLOCAL_AMFLAGS Sometimes you need to run @code{aclocal} with an argument like @code{-I} to tell it where to find @file{.m4} files. Since sometimes @code{make} will automatically run @code{aclocal}, you need a way to specify these arguments. You can do this by defining @code{ACLOCAL_AMFLAGS}; this holds arguments which are passed verbatim to @code{aclocal}. This variable is only useful in the top-level @file{Makefile.am}. @vindex CONFIG_STATUS_DEPENDENCIES @vindex CONFIGURE_DEPENDENCIES @cindex @file{version.sh}, example @cindex @file{version.m4}, example Sometimes it is convenient to supplement the rebuild rules for @file{configure} or @file{config.status} with additional dependencies. The variables @code{CONFIGURE_DEPENDENCIES} and @code{CONFIG_STATUS_DEPENDENCIES} can be used to list these extra dependencies. These variable should be defined in all @file{Makefile}s of the tree (because these two rebuild rules are output in all them), so it is safer and easier to @code{AC_SUBST} them from @file{configure.ac}. For instance the following statement will cause @file{configure} to be rerun each time @file{version.sh} is changed. @example AC_SUBST([CONFIG_STATUS_DEPENDENCIES], ['$(top_srcdir)/version.sh']) @end example @noindent Note the @code{$(top_srcdir)/} in the filename. Since this variable is to be used in all @file{Makefile}s, its value must be sensible at any level in the build hierarchy. Beware not to mistake @code{CONFIGURE_DEPENDENCIES} for @code{CONFIG_STATUS_DEPENDENCIES}. @code{CONFIGURE_DEPENDENCIES} adds dependencies to the @file{configure} rule, whose effect is to run @code{autoconf}. This variable should be seldom used, because @code{automake} already tracks @code{m4_include}d files. However it can be useful when playing tricky games with @code{m4_esyscmd} or similar non-recommendable macros with side effects. @code{CONFIG_STATUS_DEPENDENCIES} adds dependencies to the @file{config.status} rule, whose effect is to run @file{configure}. This variable should therefore carry any non-standard source that may be read as a side effect of running configure, like @file{version.sh} in the example above. Speaking of @file{version.sh} scripts, we recommend against them today. They are mainly used when the version of a package is updated automatically by a script (e.g., in daily builds). Here is what some old-style @file{configure.ac}s may look like: @example AC_INIT . $srcdir/version.sh AM_INIT_AUTOMAKE([name], $VERSION_NUMBER) @dots{} @end example @noindent Here, @file{version.sh} is a shell fragment that sets @code{VERSION_NUMBER}. The problem with this example is that @code{automake} cannot track dependencies (listing @file{version.sh} in @code{CONFIG_STATUS_DEPENDENCIES}, and distributing this file is up to the user), and that it uses the obsolete form of @code{AC_INIT} and @code{AM_INIT_AUTOMAKE}. Upgrading to the new syntax is not straightforward, because shell variables are not allowed in @code{AC_INIT}'s arguments. We recommend that @file{version.sh} be replaced by an M4 file that is included by @file{configure.ac}: @example m4_include([version.m4]) AC_INIT([name], VERSION_NUMBER) AM_INIT_AUTOMAKE @dots{} @end example @noindent Here @file{version.m4} could contain something like @code{m4_define([VERSION_NUMBER], [1.2])}. The advantage of this second form is that @code{automake} will take care of the dependencies when defining the rebuild rule, and will also distribute the file automatically. An inconvenience is that @code{autoconf} will now be rerun each time the version number is bumped, when only @file{configure} had to be rerun in the previous setup. @node Options @chapter Changing Automake's Behavior Various features of Automake can be controlled by options in the @file{Makefile.am}. Such options are applied on a per-@file{Makefile} basis when listed in a special @file{Makefile} variable named @code{AUTOMAKE_OPTIONS}. They are applied globally to all processed @file{Makefiles} when listed in the first argument of @code{AM_INIT_AUTOMAKE} in @file{configure.ac}. Currently understood options are: @vindex AUTOMAKE_OPTIONS @table @asis @item @code{gnits} @itemx @code{gnu} @itemx @code{foreign} @itemx @code{cygnus} @cindex Option, gnits @cindex Option, gnu @cindex Option, foreign @cindex Option, cygnus Set the strictness as appropriate. The @code{gnits} option also implies @code{readme-alpha} and @code{check-news}. @item @code{ansi2knr} @itemx @code{@var{path}/ansi2knr} @cindex Option, ansi2knr Turn on automatic de-ANSI-fication. @xref{ANSI}. If preceded by a path, the generated @file{Makefile.in} will look in the specified directory to find the @file{ansi2knr} program. The path should be a relative path to another directory in the same distribution (Automake currently does not check this). @item @code{check-news} @cindex Option, check-news Cause @code{make dist} to fail unless the current version number appears in the first few lines of the @file{NEWS} file. @item @code{dejagnu} @cindex Option, dejagnu Cause @code{dejagnu}-specific rules to be generated. @xref{Tests}. @item @code{dist-bzip2} @cindex Option, dist-bzip2 Hook @code{dist-bzip2} to @code{dist}. @trindex dist-bzip2 @item @code{dist-shar} @cindex Option, dist-shar Hook @code{dist-shar} to @code{dist}. @trindex dist-shar @item @code{dist-zip} @cindex Option, dist-zip Hook @code{dist-zip} to @code{dist}. @trindex dist-zip @item @code{dist-tarZ} @cindex Option, dist-tarZ Hook @code{dist-tarZ} to @code{dist}. @trindex dist-tarZ @item @code{filename-length-max=99} @cindex Option, filename-length-max=99 @trindex filename-length-max=99 Abort if filenames longer than 99 characters are found during @code{make dist}. Such long filenames are generally considered not to be portable in tarballs. See the @code{tar-v7} and @code{tar-ustar} options below. This option should be used in the top-level @file{Makefile.am} or as an argument of @code{AM_INIT_AUTOMAKE} in @file{configure.ac}, it will be ignored otherwise. @item @code{no-define} @cindex Option, no-define This options is meaningful only when passed as an argument to @code{AM_INIT_AUTOMAKE}. It will prevent the @code{PACKAGE} and @code{VERSION} variables to be @code{AC_DEFINE}d. @item @code{no-dependencies} @cindex Option, no-dependencies This is similar to using @samp{--include-deps} on the command line, but is useful for those situations where you don't have the necessary bits to make automatic dependency tracking work @xref{Dependencies}. In this case the effect is to effectively disable automatic dependency tracking. @item @code{no-dist} @cindex Option, no-dist Don't emit any code related to @code{dist} target. This is useful when a package has its own method for making distributions. @item @code{no-dist-gzip} @cindex Option, no-dist-gzip Do not hook @code{dist-gzip} to @code{dist}. @trindex no-dist-gzip @item @code{no-exeext} @cindex Option, no-exeext If your @file{Makefile.am} defines a rule for target @samp{foo}, it will override a rule for a target named @samp{foo$(EXEEXT)}. This is necessary when @code{EXEEXT} is found to be empty. However, by default automake will generate an error for this use. The @code{no-exeext} option will disable this error. This is intended for use only where it is known in advance that the package will not be ported to Windows, or any other operating system using extensions on executables. @item @code{no-installinfo} @cindex Option, no-installinfo The generated @file{Makefile.in} will not cause info pages to be built or installed by default. However, @code{info} and @code{install-info} targets will still be available. This option is disallowed at @samp{GNU} strictness and above. @trindex info @trindex install-info @item @code{no-installman} @cindex Option, no-installman The generated @file{Makefile.in} will not cause man pages to be installed by default. However, an @code{install-man} target will still be available for optional installation. This option is disallowed at @samp{GNU} strictness and above. @trindex install-man @item @code{nostdinc} @cindex Option, nostdinc This option can be used to disable the standard @samp{-I} options which are ordinarily automatically provided by Automake. @item @code{no-texinfo.tex} @cindex Option, no-texinfo Don't require @file{texinfo.tex}, even if there are texinfo files in this directory. @item @code{readme-alpha} @cindex Option, readme-alpha If this release is an alpha release, and the file @file{README-alpha} exists, then it will be added to the distribution. If this option is given, version numbers are expected to follow one of two forms. The first form is @samp{@var{MAJOR}.@var{MINOR}.@var{ALPHA}}, where each element is a number; the final period and number should be left off for non-alpha releases. The second form is @samp{@var{MAJOR}.@var{MINOR}@var{ALPHA}}, where @var{ALPHA} is a letter; it should be omitted for non-alpha releases. @item @code{std-options} @cindex Options, std-options @cindex make installcheck Make the @code{installcheck} rule check that installed scripts and programs support the @code{--help} and @code{--version} options. This also provides a basic check that the program's run-time dependencies are satisfied after installation. @vindex AM_INSTALLCHECK_STD_OPTIONS_EXEMPT In a few situations, programs (or scripts) have to be exempted from this test. For instance @command{false} (from GNU sh-utils) is never successful, even for @code{--help} or @code{--version}. You can list such programs in the variable @code{AM_INSTALLCHECK_STD_OPTIONS_EXEMPT}. Programs (not scripts) listed in this variable should be suffixed by @code{$(EXEEXT)} for the sake of Win32 or OS/2. For instance suppose we build @code{false} as a program but @code{true.sh} as a script, and that neither of them support @code{--help} or @code{--version}: @example AUTOMAKE_OPTIONS = std-options bin_PROGRAMS = false ... bin_SCRIPTS = true.sh ... AM_INSTALLCHECK_STD_OPTIONS_EXEMPT = false$(EXEEXT) true.sh @end example @item @code{subdir-objects} If this option is specified, then objects are placed into the subdirectory of the build directory corresponding to the subdirectory of the source file. For instance if the source file is @file{subdir/file.cxx}, then the output file would be @file{subdir/file.o}. @item @code{tar-v7} @itemx @code{tar-ustar} @itemx @code{tar-pax} @cindex Option, tar-v7 @cindex Option, tar-ustar @cindex Option, tar-pax @cindex tar formats @cindex v7 tar format @cindex ustar format @cindex pax format @trindex tar-v7 @trindex tar-ustar @trindex tar-pax These three mutually exclusive options select the tar format to use when generating tarballs with @code{make dist}. (The tar file created is then compressed according to the set of @code{no-dist-gzip}, @code{dist-bzip2} and @code{dist-tarZ} options in use.) These options must be passed as argument to @code{AM_INIT_AUTOMAKE} (@pxref{Macros}) because they can causes new configure check to be performed. Automake will complain if it sees such option in a @code{AUTOMAKE_OPTIONS} variable. @code{tar-v7} selects the old V7 tar format. This is the historical default. This antiquated format is understood by all tar implementations and supports filenames with up to 99 characters. When given longer filenames some tar implementations will diagnose the problem while other will generate broken tarballs or use non-portable extensions. Furthermore, the V7 format cannot store empty directories. When using this format, consider using the @code{filename-length-max=99} option to catch filenames too long. @code{tar-ustar} selects the ustar format defined by POSIX 1003.1-1988. This format is believed to be old enough to be portable. It fully supports empty directories. It can stores filenames with up to 256 characters, provided that the filename can be split at directory separator in two parts, first of them being at most 155 bytes long. So, in most cases the maximum file name length will be shorter than 256 characters. However you may run against broken tar implementations that incorrectly handle filenames longer than 99 characters (please report them to @email{bug-automake@@gnu.org} so we can document this accurately). @code{tar-pax} selects the new pax interchange format defined by POSIX 1003.1-2001. It does not limit the length of filenames. However, this format is very young and should probably be restricted to packages which target only very modern platforms. There are moves to change the pax format in an upward-compatible way, so this option may refer to a more recent version in the future. @xref{Formats, , Controlling the Archive Format, tar, GNU Tar}, for further discussion about tar formats. @code{configure} knows several ways to construct these formats. It will not abort if it cannot find a tool up to the task (so that the package can still be built), but @code{make dist} will fail. @item @var{version} @cindex Option, version A version number (e.g. @samp{0.30}) can be specified. If Automake is not newer than the version specified, creation of the @file{Makefile.in} will be suppressed. @item @code{-W@var{category}} or @code{--warnings=@var{category}} @cindex Option, warnings These options behave exactly like their command-line counterpart (@pxref{Invoking Automake}). This allows you to enable or disable some warning categories on a per-file basis. You can also setup some warnings for your entire project; for instance try @code{AM_INIT_AUTOMAKE([-Wall])} in your @file{configure.ac}. @end table Unrecognized options are diagnosed by @code{automake}. If you want an option to apply to all the files in the tree, you can use the @code{AM_INIT_AUTOMAKE} macro in @file{configure.ac}. @xref{Macros}. @node Miscellaneous @chapter Miscellaneous Rules There are a few rules and variables that didn't fit anywhere else. @menu * Tags:: Interfacing to etags and mkid * Suffixes:: Handling new file extensions * Multilibs:: Support for multilibs. @end menu @node Tags @section Interfacing to @code{etags} @cindex TAGS support Automake will generate rules to generate @file{TAGS} files for use with GNU Emacs under some circumstances. @trindex tags If any C, C++ or Fortran 77 source code or headers are present, then @code{tags} and @code{TAGS} rules will be generated for the directory. All files listed using the @code{_SOURCES}, @code{_HEADERS}, and @code{_LISP} primaries will be used to generate tags. Note that generated source files that are not distributed must be declared in variables like @code{nodist_noinst_HEADERS} or @code{nodist_@var{prog}_SOURCES} or they will be ignored. At the topmost directory of a multi-directory package, a @code{tags} rule will be output which, when run, will generate a @file{TAGS} file that includes by reference all @file{TAGS} files from subdirectories. The @code{tags} rule will also be generated if the variable @code{ETAGS_ARGS} is defined. This variable is intended for use in directories which contain taggable source that @code{etags} does not understand. The user can use the @code{ETAGSFLAGS} to pass additional flags to @code{etags}; @code{AM_ETAGSFLAGS} is also available for use in @file{Makefile.am}. @vindex ETAGS_ARGS @vindex ETAGSFLAGS @vindex AM_ETAGSFLAGS Here is how Automake generates tags for its source, and for nodes in its Texinfo file: @example ETAGS_ARGS = automake.in --lang=none \ --regex='/^@@node[ \t]+\([^,]+\)/\1/' automake.texi @end example If you add filenames to @samp{ETAGS_ARGS}, you will probably also want to set @samp{TAGS_DEPENDENCIES}. The contents of this variable are added directly to the dependencies for the @code{tags} rule. @vindex TAGS_DEPENDENCIES Automake also generates a @code{ctags} rule which can be used to build @command{vi}-style @file{tags} files. The variable @code{CTAGS} is the name of the program to invoke (by default @samp{ctags}); @code{CTAGSFLAGS} can be used by the user to pass additional flags, and @code{AM_CTAGSFLAGS} can be used by the @file{Makefile.am}. Automake will also generate an @code{ID} rule which will run @code{mkid} on the source. This is only supported on a directory-by-directory basis. @trindex id Automake also supports the @uref{http://www.gnu.org/software/global/, GNU Global Tags program}. The @code{GTAGS} rule runs Global Tags automatically and puts the result in the top build directory. The variable @code{GTAGS_ARGS} holds arguments which are passed to @code{gtags}. @vindex GTAGS_ARGS @node Suffixes @section Handling new file extensions @cindex Adding new SUFFIXES @cindex SUFFIXES, adding @vindex SUFFIXES It is sometimes useful to introduce a new implicit rule to handle a file type that Automake does not know about. For instance, suppose you had a compiler which could compile @samp{.foo} files to @samp{.o} files. You would simply define an suffix rule for your language: @example .foo.o: foocc -c -o $@@ $< @end example Then you could directly use a @samp{.foo} file in a @samp{_SOURCES} variable and expect the correct results: @example bin_PROGRAMS = doit doit_SOURCES = doit.foo @end example This was the simpler and more common case. In other cases, you will have to help Automake to figure which extensions you are defining your suffix rule for. This usually happens when your extensions does not start with a dot. Then, all you have to do is to put a list of new suffixes in the @code{SUFFIXES} variable @strong{before} you define your implicit rule. For instance the following definition prevents Automake to misinterpret @samp{.idlC.cpp:} as an attempt to transform @samp{.idlC} into @samp{.cpp}. @example SUFFIXES = .idl C.cpp .idlC.cpp: # whatever @end example As you may have noted, the @code{SUFFIXES} variable behaves like the @code{.SUFFIXES} special target of @code{make}. You should not touch @code{.SUFFIXES} yourself, but use @code{SUFFIXES} instead and let Automake generate the suffix list for @code{.SUFFIXES}. Any given @code{SUFFIXES} go at the start of the generated suffixes list, followed by Automake generated suffixes not already in the list. @node Multilibs @section Support for Multilibs Automake has support for an obscure feature called multilibs. A @dfn{multilib} is a library which is built for multiple different ABIs at a single time; each time the library is built with a different target flag combination. This is only useful when the library is intended to be cross-compiled, and it is almost exclusively used for compiler support libraries. The multilib support is still experimental. Only use it if you are familiar with multilibs and can debug problems you might encounter. @node Include @chapter Include @cmindex include @cindex Including Makefile fragment @cindex Makefile fragment, including Automake supports an @code{include} directive which can be used to include other @file{Makefile} fragments when @code{automake} is run. Note that these fragments are read and interpreted by @code{automake}, not by @code{make}. As with conditionals, @code{make} has no idea that @code{include} is in use. There are two forms of @code{include}: @table @code @item include $(srcdir)/file Include a fragment which is found relative to the current source directory. @item include $(top_srcdir)/file Include a fragment which is found relative to the top source directory. @end table Note that if a fragment is included inside a conditional, then the condition applies to the entire contents of that fragment. Makefile fragments included this way are always distributed because there are needed to rebuild @file{Makefile.in}. @node Conditionals @chapter Conditionals @cindex Conditionals Automake supports a simple type of conditionals. @cvindex AM_CONDITIONAL Before using a conditional, you must define it by using @code{AM_CONDITIONAL} in the @code{configure.ac} file (@pxref{Macros}). @defmac AM_CONDITIONAL (@var{conditional}, @var{condition}) The conditional name, @var{conditional}, should be a simple string starting with a letter and containing only letters, digits, and underscores. It must be different from @samp{TRUE} and @samp{FALSE} which are reserved by Automake. The shell @var{condition} (suitable for use in a shell @code{if} statement) is evaluated when @code{configure} is run. Note that you must arrange for @emph{every} @code{AM_CONDITIONAL} to be invoked every time @code{configure} is run -- if @code{AM_CONDITIONAL} is run conditionally (e.g., in a shell @code{if} statement), then the result will confuse automake. @end defmac @cindex --enable-debug, example @cindex Example conditional --enable-debug @cindex Conditional example, --enable-debug Conditionals typically depend upon options which the user provides to the @code{configure} script. Here is an example of how to write a conditional which is true if the user uses the @samp{--enable-debug} option. @example AC_ARG_ENABLE(debug, [ --enable-debug Turn on debugging], [case "$@{enableval@}" in yes) debug=true ;; no) debug=false ;; *) AC_MSG_ERROR(bad value $@{enableval@} for --enable-debug) ;; esac],[debug=false]) AM_CONDITIONAL(DEBUG, test x$debug = xtrue) @end example Here is an example of how to use that conditional in @file{Makefile.am}: @cmindex if @cmindex endif @cmindex else @example if DEBUG DBG = debug else DBG = endif noinst_PROGRAMS = $(DBG) @end example This trivial example could also be handled using EXTRA_PROGRAMS (@pxref{Conditional Programs}). You may only test a single variable in an @code{if} statement, possibly negated using @samp{!}. The @code{else} statement may be omitted. Conditionals may be nested to any depth. You may specify an argument to @code{else} in which case it must be the negation of the condition used for the current @code{if}. Similarly you may specify the condition which is closed by an @code{end}: @example if DEBUG DBG = debug else !DEBUG DBG = endif !DEBUG @end example @noindent Unbalanced conditions are errors. Note that conditionals in Automake are not the same as conditionals in GNU Make. Automake conditionals are checked at configure time by the @file{configure} script, and affect the translation from @file{Makefile.in} to @file{Makefile}. They are based on options passed to @file{configure} and on results that @file{configure} has discovered about the host system. GNU Make conditionals are checked at @code{make} time, and are based on variables passed to the make program or defined in the @file{Makefile}. Automake conditionals will work with any make program. @node Gnits @chapter The effect of @code{--gnu} and @code{--gnits} @cindex --gnu, required files @cindex --gnu, complete description The @samp{--gnu} option (or @samp{gnu} in the @samp{AUTOMAKE_OPTIONS} variable) causes @code{automake} to check the following: @itemize @bullet @item The files @file{INSTALL}, @file{NEWS}, @file{README}, @file{AUTHORS}, and @file{ChangeLog}, plus one of @file{COPYING.LIB}, @file{COPYING.LESSER} or @file{COPYING}, are required at the topmost directory of the package. @item The options @samp{no-installman} and @samp{no-installinfo} are prohibited. @end itemize Note that this option will be extended in the future to do even more checking; it is advisable to be familiar with the precise requirements of the GNU standards. Also, @samp{--gnu} can require certain non-standard GNU programs to exist for use by various maintainer-only rules; for instance in the future @code{pathchk} might be required for @samp{make dist}. @cindex --gnits, complete description The @samp{--gnits} option does everything that @samp{--gnu} does, and checks the following as well: @itemize @bullet @item @samp{make installcheck} will check to make sure that the @code{--help} and @code{--version} really print a usage message and a version string, respectively. This is the @code{std-options} option (@pxref{Options}). @item @samp{make dist} will check to make sure the @file{NEWS} file has been updated to the current version. @item @samp{VERSION} is checked to make sure its format complies with Gnits standards. @c FIXME xref when standards are finished @item @cindex README-alpha If @samp{VERSION} indicates that this is an alpha release, and the file @file{README-alpha} appears in the topmost directory of a package, then it is included in the distribution. This is done in @samp{--gnits} mode, and no other, because this mode is the only one where version number formats are constrained, and hence the only mode where Automake can automatically determine whether @file{README-alpha} should be included. @item The file @file{THANKS} is required. @end itemize @node Cygnus @chapter The effect of @code{--cygnus} @cindex Cygnus strictness Some packages, notably GNU GCC and GNU gdb, have a build environment originally written at Cygnus Support (subsequently renamed Cygnus Solutions, and then later purchased by Red Hat). Packages with this ancestry are sometimes referred to as ``Cygnus'' trees. A Cygnus tree has slightly different rules for how a @file{Makefile.in} is to be constructed. Passing @samp{--cygnus} to @code{automake} will cause any generated @file{Makefile.in} to comply with Cygnus rules. Here are the precise effects of @samp{--cygnus}: @itemize @bullet @item Info files are always created in the build directory, and not in the source directory. @item @file{texinfo.tex} is not required if a Texinfo source file is specified. The assumption is that the file will be supplied, but in a place that Automake cannot find. This assumption is an artifact of how Cygnus packages are typically bundled. @item @samp{make dist} is not supported, and the rules for it are not generated. Cygnus-style trees use their own distribution mechanism. @item Certain tools will be searched for in the build tree as well as in the user's @samp{PATH}. These tools are @code{runtest}, @code{expect}, @code{makeinfo} and @code{texi2dvi}. @item @code{--foreign} is implied. @item The options @samp{no-installinfo} and @samp{no-dependencies} are implied. @item The macros @samp{AM_MAINTAINER_MODE} and @samp{AM_CYGWIN32} are required. @item The @code{check} target doesn't depend on @code{all}. @end itemize GNU maintainers are advised to use @samp{gnu} strictness in preference to the special Cygnus mode. Some day, perhaps, the differences between Cygnus trees and GNU trees will disappear (for instance, as GCC is made more standards compliant). At that time the special Cygnus mode will be removed. @node Not Enough @chapter When Automake Isn't Enough In some situations, where Automake is not up to one task, one has to resort to handwritten rules or even handwritten @file{Makefile}s. @menu * Extending:: Adding new rules or overriding existing ones. * Third-Party Makefiles:: Integrating Non-Automake @file{Makefile}s. @end menu @node Extending @section Extending Automake Rules With some minor exceptions (like @code{_PROGRAMS} variables being rewritten to append @code{$(EXEEXT)}), the contents of a @file{Makefile.am} is copied to @file{Makefile.in} verbatim. @cindex copying semantics These copying semantics means that many problems can be worked around by simply adding some @code{make} variables and rules to @file{Makefile.am}. Automake will ignore these additions. @cindex conflicting definitions @cindex rules, conflicting @cindex variables, conflicting @cindex definitions, conflicts Since a @file{Makefile.in} is built from data gathered from three different places (@file{Makefile.am}, @file{configure.ac}, and @command{automake} itself), it is possible to have conflicting definitions of rules or variables. When building @file{Makefile.in} the following priorities are respected by @command{automake} to ensure the user always have the last word. User defined variables in @file{Makefile.am} have priority over variables @code{AC_SUBST}ed from @file{configure.ac}, and @code{AC_SUBST}ed variables have priority over @command{automake}-defined variables. As far rules are concerned, a user-defined rule overrides any @command{automake}-defined rule for the same target. @cindex overriding rules @cindex overriding semantics @cindex rules, overriding These overriding semantics make it possible to fine tune some default settings of Automake, or replace some of its rules. Overriding Automake rules is often inadvisable, particularly in the topmost directory of a package with subdirectories. The @code{-Woverride} option (@pxref{Invoking Automake}) comes handy to catch overridden definitions. Note that Automake does not make any difference between rules with commands and rules that only specify dependencies. So it is not possible to append new dependencies to an @code{automake}-defined target without redefining the entire rule. @cindex -local targets @cindex local targets However, various useful targets have a @samp{-local} version you can specify in your @file{Makefile.in}. Automake will supplement the standard target with these user-supplied targets. @trindex all @trindex all-local @trindex info @trindex info-local @trindex dvi @trindex dvi-local @trindex ps @trindex ps-local @trindex pdf @trindex pdf-local @trindex html @trindex html-local @trindex check @trindex check-local @trindex install @trindex install-data-local @trindex install-exec @trindex install-exec-local @trindex uninstall @trindex uninstall-local @trindex mostlyclean @trindex mostlyclean-local @trindex clean @trindex clean-local @trindex distclean @trindex distclean-local @trindex installdirs @trindex installdirs-local @trindex installcheck @trindex installcheck-local The targets that support a local version are @code{all}, @code{info}, @code{dvi}, @code{ps}, @code{pdf}, @code{html}, @code{check}, @code{install-data}, @code{install-exec}, @code{uninstall}, @code{installdirs}, @code{installcheck} and the various @code{clean} targets (@code{mostlyclean}, @code{clean}, @code{distclean}, and @code{maintainer-clean}). Note that there are no @code{uninstall-exec-local} or @code{uninstall-data-local} targets; just use @code{uninstall-local}. It doesn't make sense to uninstall just data or just executables. For instance, here is one way to install a file in @file{/etc}: @example install-data-local: $(INSTALL_DATA) $(srcdir)/afile $(DESTDIR)/etc/afile @end example @cindex -hook targets @cindex hook targets Some rule also have a way to run another rule, called a @dfn{hook}, after their work is done. The hook is named after the principal target, with @samp{-hook} appended. The targets allowing hooks are @code{install-data}, @code{install-exec}, @code{uninstall}, @code{dist}, and @code{distcheck}. @trindex install-data-hook @trindex install-exec-hook @trindex uninstall-hook @trindex dist-hook For instance, here is how to create a hard link to an installed program: @example install-exec-hook: ln $(DESTDIR)$(bindir)/program$(EXEEXT) \ $(DESTDIR)$(bindir)/proglink$(EXEEXT) @end example Although cheaper and more portable than symbolic links, hard links will not work everywhere (for instance OS/2 does not have @command{ln}). Ideally you should fall back to @code{cp -p} when @code{ln} does not work. An easy way, if symbolic links are acceptable to you, is to add @code{AC_PROG_LN_S} to @file{configure.ac} (@pxref{Particular Programs, , Particular Program Checks, autoconf, The Autoconf Manual}) and use @code{$(LN_S)} in @file{Makefile.am}. @cindex versioned binaries, installing @cindex installing versioned binaries @cindex LN_S example For instance, here is how you could install a versioned copy of a program using @code{$(LN_S)}: @example install-exec-hook: cd $(DESTDIR)$(bindir) && \ mv -f prog$(EXEEXT) prog-$(VERSION)$(EXEEXT) && \ $(LN_S) prog-$(VERSION)$(EXEEXT) prog$(EXEEXT) @end example Note that we rename the program so that a new version will erase the symbolic link, not the real binary. Also we @code{cd} into the destination directory in order to create relative links. @c FIXME should include discussion of variables you can use in these @c rules @node Third-Party Makefiles @section Third-Party @file{Makefile}s @cindex Third-party packages, interfacing with @cindex Interfacing with third-party packages In most projects all @file{Makefile}s are generated by Automake. In some cases, however, projects need to embed subdirectories with handwritten @file{Makefile}s. For instance one subdirectory could be a third-party project with its own build system, not using Automake. It is possible to list arbitrary directories in @code{SUBDIRS} or @code{DIST_SUBDIRS} provided each of these directories has a @file{Makefile} that recognizes all the following recursive targets. @cindex recursive targets and third-party @file{Makefile}s When a user runs one of these targets, that target is run recursively in all subdirectories. This is why it is important that even third-party @file{Makefile}s support them. @table @code @item all Compile the entire package. This is the default target in Automake-generated @file{Makefile}s, but it does not need to be the default in third-party @file{Makefile}s. @item distdir @trindex distdir @vindex distdir @vindex top_distdir Copy files to distribute into @code{$(distdir)}, before a tarball is constructed. Of course this target is not required if the @code{no-dist} option (@pxref{Options}) is used. The variables @code{$(top_distdir)} and @code{$(distdir)} (@pxref{Dist}) will be passed from the outer package to the subpackage when the @code{distdir} target is invoked. These two variables have been adjusted for the directory which is being recursed into, so they are ready to use. @item install @itemx install-data @itemx install-exec @itemx uninstall Install or uninstall files (@pxref{Install}). @item install-info Install only the Texinfo documentation (@pxref{Texinfo}). @item installdirs Create install directories, but do not install any files. @item check @itemx installcheck Check the package (@pxref{Tests}). @item mostlyclean @itemx clean @itemx distclean @itemx maintainer-clean Cleaning rules (@pxref{Clean}). @item dvi @itemx pdf @itemx ps @itemx info @itemx html Build the documentation in various formats (@pxref{Texinfo}). @item tags @itemx ctags Build @code{TAGS} and @code{CTAGS} (@pxref{Tags}). @end table If you have ever used Gettext in a project, this is a good example of how third-party @file{Makefile}s can be used with Automake. The @file{Makefile}s @command{gettextize} puts in the @file{po/} and @file{intl/} directories are handwritten @file{Makefile}s that implement all these targets. That way they can be added to @code{SUBDIRS} in Automake packages. Directories which are only listed in @code{DIST_SUBDIRS} but not in @code{SUBDIRS} need only the @code{distclean}, @code{maintainer-clean}, and @code{distdir} rules (@pxref{Conditional Subdirectories}). Usually, many of these rules are irrelevant to the third-party subproject, but they are required for the whole package to work. It's OK to have a rule that does nothing, so if you are integrating a third-party project with no documentation or tag support, you could simply augment its @file{Makefile} as follows: @example EMPTY_AUTOMAKE_TARGETS = dvi pdf ps info html tags ctags .PHONY: $(EMPTY_AUTOMAKE_TARGETS) $(EMPTY_AUTOMAKE_TARGETS): @end example Another aspect of integrating third-party build systems is whether they support VPATH builds. Obviously if the subpackage does not support VPATH builds the whole package will not support VPATH builds. This in turns means that @code{make distcheck} will not work, because it relies on VPATH builds. Some people can live without this (actually, many Automake users have never heard of @code{make distcheck}). Other people may prefer to revamp the existing @file{Makefile}s to support VPATH. Doing so does not necessarily require Automake, only Autoconf is needed (@pxref{Build Directories, , Build Directories, autoconf, The Autoconf Manual}). The necessary substitutions: @code{@@scrdir@@}, @code{@@top_srcdir@@}, and @code{@@top_buildir@@} are defined by @file{configure} when it processes a @file{Makefile} (@pxref{Preset Output Variables, , Preset Output Variables, autoconf, The Autoconf Manual}), they are not computed by the Makefile like the aforementioned @code{$(distdir)} and @code{$(top_distdir)} variables.. It is sometimes inconvenient to modify a third-party @file{Makefile} to introduce the above required targets. For instance one may want to keep the third-party sources untouched to ease upgrades to new versions. @cindex @file{GNUmakefile} including @file{Makefile} Here are two other ideas. If GNU make is assumed, one possibility is to add to that subdirectory a @file{GNUmakefile} that defines the required targets and include the third-party @file{Makefile}. For this to work in VPATH builds, @file{GNUmakefile} must lie in the build directory; the easiest way to do this is to write a @file{GNUmakefile.in} instead, and have it processed with @code{AC_CONFIG_FILES} from the outer package. For example if we assume @file{Makefile} defines all targets except the documentation targets, and that the @code{check} target is actually called @code{test}, we could write @file{GNUmakefile} (or @file{GNUmakefile.in}) like this: @example # First, include the real Makefile include Makefile # Then, define the other targets needed by Automake Makefiles. .PHONY: dvi pdf ps info html check dvi pdf ps info html: check: test @end example @cindex Proxy @file{Makefile} for third-party packages A similar idea that does not use @code{include} is to write a proxy @file{Makefile} that dispatches rules to the real @file{Makefile}, either with @code{$(MAKE) -f Makefile.real $(AM_MAKEFLAGS) target} (if it's OK to rename the original @file{Makefile}) or with @code{cd subdir && $(MAKE) $(AM_MAKEFLAGS) target} (if it's OK to store the subdirectory project one directory deeper). The good news is that this proxy @file{Makefile} can be generated with Automake. All we need are -local targets (@pxref{Extending}) that perform the dispatch. Of course the other Automake features are available, so you could decide to let Automake perform distribution or installation. Here is a possible @file{Makefile.am}: @example all-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) all check-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) test clean-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) clean # Assuming the package knows how to install itself install-data-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-data install-exec-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-exec uninstall-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) uninstall # Distribute files from here. EXTRA_DIST = subdir/Makefile subdir/program.c ... @end example Pushing this idea to the extreme, it is also possible to ignore the subproject build system and build everything from this proxy @file{Makefile.am}. This might sounds very sensible if you need VPATH builds but the subproject does not support them. @node Distributing @chapter Distributing @file{Makefile.in}s Automake places no restrictions on the distribution of the resulting @file{Makefile.in}s. We still encourage software authors to distribute their work under terms like those of the GPL, but doing so is not required to use Automake. Some of the files that can be automatically installed via the @code{--add-missing} switch do fall under the GPL@. However, these also have a special exception allowing you to distribute them with your package, regardless of the licensing you choose. @node API versioning @chapter Automake API versioning New Automake releases usually include bug fixes and new features. Unfortunately they may also introduce new bugs and incompatibilities. This makes four reasons why a package may require a particular Automake version. Things get worse when maintaining a large tree of packages, each one requiring a different version of Automake. In the past, this meant that any developer (and sometime users) had to install several versions of Automake in different places, and switch @samp{$PATH} appropriately for each package. Starting with version 1.6, Automake installs versioned binaries. This means you can install several versions of Automake in the same @samp{$prefix}, and can select an arbitrary Automake version by running @samp{automake-1.6} or @samp{automake-1.7} without juggling with @samp{$PATH}. Furthermore, @file{Makefile}'s generated by Automake 1.6 will use @samp{automake-1.6} explicitly in their rebuild rules. The number @samp{1.6} in @samp{automake-1.6} is Automake's API version, not Automake's version. If a bug fix release is made, for instance Automake 1.6.1, the API version will remain 1.6. This means that a package which work with Automake 1.6 should also work with 1.6.1; after all, this is what people expect from bug fix releases. If your package relies on a feature or a bug fix introduced in a release, you can pass this version as an option to Automake to ensure older releases will not be used. For instance, use this in your @file{configure.ac}: @example AM_INIT_AUTOMAKE(1.6.1) dnl Require Automake 1.6.1 or better. @end example @noindent or, in a particular @file{Makefile.am}: @example AUTOMAKE_OPTIONS = 1.6.1 # Require Automake 1.6.1 or better. @end example @noindent Automake will print an error message if its version is older than the requested version. @heading What is in the API Automake's programming interface is not easy to define. Basically it should include at least all @strong{documented} variables and targets that a @samp{Makefile.am} author can use, any behavior associated with them (e.g. the places where @samp{-hook}'s are run), the command line interface of @samp{automake} and @samp{aclocal}, @dots{} @heading What is not in the API Every undocumented variable, target, or command line option, is not part of the API@. You should avoid using them, as they could change from one version to the other (even in bug fix releases, if this helps to fix a bug). If it turns out you need to use such a undocumented feature, contact @email{automake@@gnu.org} and try to get it documented and exercised by the test-suite. @node Upgrading @chapter Upgrading a Package to a Newer Automake Version Automake maintains three kind of files in a package. @itemize @item @file{aclocal.m4} @item @file{Makefile.in}s @item auxiliary tools like @file{install-sh} or @file{py-compile} @end itemize @file{aclocal.m4} is generated by @command{aclocal} and contains some Automake-supplied M4 macros. Auxiliary tools are installed by @samp{automake --add-missing} when needed. @file{Makefile.in}s are built from @file{Makefile.am} by @command{automake}, and rely on the definitions of the M4 macros put in @file{aclocal.m4} as well as the behavior of the auxiliary tools installed. Because all these files are closely related, it is important to regenerate all of them when upgrading to a newer Automake release. The usual way to do that is @example aclocal # with any option needed (such a -I m4) autoconf automake --add-missing --force-missing @end example @noindent or more conveniently: @example autoreconf -vfi @end example The use of @code{--force-missing} ensures that auxiliary tools will be overridden by new versions (@pxref{Invoking Automake}). It is important to regenerate all these files each time Automake is upgraded, even between bug fixes releases. For instance it is not unusual for a bug fix to involve changes to both the rules generated in @file{Makefile.in} and the supporting M4 macros copied to @file{aclocal.m4}. Presently @command{automake} is able to diagnose situations where @file{aclocal.m4} has been generated with another version of @command{aclocal}. However it never checks whether auxiliary scripts are up-to-date. In other words, @command{automake} will tell you when @command{aclocal} needs to be rerun, but it will never diagnose a missing @code{--force-missing}. Before upgrading to a new major release, it is a good idea to read the file @file{NEWS}. This file lists all changes between releases: new features, obsolete constructs, known incompatibilities, and workarounds. @node FAQ @chapter Frequently Asked Questions about Automake This chapter covers some questions that often come up on the mailing lists. @menu * CVS:: CVS and generated files * maintainer-mode:: missing and AM_MAINTAINER_MODE * wildcards:: Why doesn't Automake support wildcards? * distcleancheck:: Files left in build directory after distclean * renamed objects:: Why are object files sometimes renamed? * Multiple Outputs:: Writing rules for tools with many output files @end menu @node CVS @section CVS and generated files @subsection Background: distributed generated files @cindex generated files, distributed @cindex rebuild rules Packages made with Autoconf and Automake ship with some generated files like @file{configure} or @file{Makefile.in}. These files were generated on the developer's host and are distributed so that end-users do not have to install the maintainer tools required to rebuild them. Other generated files like Lex scanners, Yacc parsers, or Info documentation, are usually distributed on similar grounds. Automake outputs rules in @file{Makefile}s to rebuild these files. For instance @command{make} will run @command{autoconf} to rebuild @file{configure} whenever @file{configure.ac} is changed. This makes development safer by ensuring a @file{configure} is never out-of-date with respect to @file{configure.ac}. As generated files shipped in packages are up-to-date, and because @command{tar} preserves times-tamps, these rebuild rules are not triggered when a user unpacks and builds a package. @subsection Background: CVS and timestamps @cindex timestamps and CVS @cindex CVS and timestamps Unless you use CVS keywords (in which case files must be updated at commit time), CVS preserves timestamp during @code{cvs commit} and @code{cvs import -d} operations. When you check out a file using @code{cvs checkout} its timestamp is set to that of the revision which is being checked out. However, during @command{cvs update}, files will have the date of the update, not the original timestamp of this revision. This is meant to make sure that @command{make} notices sources files have been updated. This times tamp shift is troublesome when both sources and generated files are kept under CVS. Because CVS processes files in alphabetical order, @file{configure.ac} will appear older than @file{configure} after a @command{cvs update} that updates both files, even if @file{configure} was newer than @file{configure.ac} when it was checked in. Calling @code{make} will then trigger a spurious rebuild of @file{configure}. @subsection Living with CVS in Autoconfiscated projects @cindex CVS and generated files @cindex generated files and CVS There are basically two clans amongst maintainers: those who keep all distributed files under CVS, including generated files, and those who keep generated files @emph{out} of CVS. @subsubheading All files in CVS @itemize @bullet @item The CVS repository contains all distributed files so you know exactly what is distributed, and you can checkout any prior version entirely. @item Maintainers can see how generated files evolve (for instance you can see what happens to your @file{Makefile.in}s when you upgrade Automake and make sure they look OK). @item Users do not need the autotools to build a checkout of the project, it works just like a released tarball. @item If users use @command{cvs update} to update their copy, instead of @command{cvs checkout} to fetch a fresh one, timestamps will be inaccurate. Some rebuild rules will be triggered and attempt to run developer tools such as @command{autoconf} or @command{automake}. Actually, calls to such tools are all wrapped into a call to the @command{missing} script discussed later (@pxref{maintainer-mode}). @command{missing} will take care of fixing the timestamps when these tools are not installed, so that the build can continue. @item In distributed development, developers are likely to have different version of the maintainer tools installed. In this case rebuilds triggered by timestamp lossage will lead to spurious changes to generated files. There are several solutions to this: @itemize @item All developers should use the same versions, so that the rebuilt files are identical to files in CVS. (This starts to be difficult when each project you work on uses different versions.) @item Or people use a script to fix the timestamp after a checkout (the GCC folks have such a script). @item Or @file{configure.ac} uses @code{AM_MAINTAINER_MODE}, which will disable all these rebuild rules by default. This is further discussed in @ref{maintainer-mode}. @end itemize @item Although we focused on spurious rebuilds, the converse can also happen. CVS's timestamp handling can also let you think an out-of-date file is up-to-date. For instance, suppose a developer has modified @file{Makefile.am} and rebuilt @file{Makefile.in}, and then decide to do a last-minute change to @file{Makefile.am} right before checking in both files (without rebuilding @file{Makefile.in} to account for the change). This last change to @file{Makefile.am} make the copy of @file{Makefile.in} out-of-date. Since CVS processes files alphabetically, when another developer @code{cvs update} his or her tree, @file{Makefile.in} will happen to be newer than @file{Makefile.am}. This other developer will not see @file{Makefile.in} is out-of-date. @end itemize @subsubheading Generated files out of CVS One way to get CVS and @code{make} working peacefully is to never store generated files in CVS, i.e., do not CVS-control files which are @code{Makefile} targets (also called @emph{derived} files). This way developers are not annoyed by changes to generated files. It does not matter if they all have different versions (assuming they are compatible, of course). And finally, timestamps are not lost, changes to sources files can't be missed as in the @file{Makefile.am}/@file{Makefile.in} example discussed earlier. The drawback is that the CVS repository is not an exact copy of what is distributed and that users now need to install various development tools (maybe even specific versions) before they can build a checkout. But, after all, CVS's job is versioning, not distribution. Allowing developers to use different versions of their tools can also hide bugs during distributed development. Indeed, developers will be using (hence testing) their own generated files, instead of the generated files that will be released actually. The developer who prepares the tarball might be using a version of the tool that produces bogus output (for instance a non-portable C file), something other developers could have noticed if they weren't using their own versions of this tool. @subsection Third-party files @cindex CVS and third-party files @cindex third-party files and CVS Another class of files not discussed here (because they do not cause timestamp issues) are files which are shipped with a package, but maintained elsewhere. For instance tools like @command{gettextize} and @command{autopoint} (from Gettext) or @command{libtoolize} (from Libtool), will install or update files in your package. These files, whether they are kept under CVS or not, raise similar concerns about version mismatch between developers' tools. The Gettext manual has a section about this, see @ref{CVS Issues, CVS Issues, Integrating with CVS, gettext, GNU gettext tools}. @node maintainer-mode @section @command{missing} and @code{AM_MAINTAINER_MODE} @subsection @command{missing} @cindex missing, purpose The @command{missing} script is a wrapper around several maintainer tools, designed to warn users if a maintainer tool is required but missing. Typical maintainer tools are @command{autoconf}, @command{automake}, @command{bison}, etc. Because file generated by these tools are shipped with the other sources of a package, these tools shouldn't be required during a user build and they are not checked for in @file{configure}. However, if for some reason a rebuild rule is triggered and involves a missing tool, @command{missing} will notice it and warn the user. Besides the warning, when a tool is missing, @command{missing} will attempt to fix timestamps in a way which allow the build to continue. For instance @command{missing} will touch @file{configure} if @command{autoconf} is not installed. When all distributed files are kept under CVS, this feature of @command{missing} allows user @emph{with no maintainer tools} to build a package off CVS, bypassing any timestamp inconsistency implied by @code{cvs update}. If the required tool is installed, @command{missing} will run it and won't attempt to continue after failures. This is correct during development: developers love fixing failures. However, users with wrong versions of maintainer tools may get an error when the rebuild rule is spuriously triggered, halting the build. This failure to let the build continue is one of the arguments of the @code{AM_MAINTAINER_MODE} advocates. @subsection @code{AM_MAINTAINER_MODE} @cindex AM_MAINTAINER_MODE, purpose @cvindex AM_MAINTAINER_MODE @code{AM_MAINTAINER_MODE} disables the so called "rebuild rules" by default. If you have @code{AM_MAINTAINER_MODE} in @file{configure.ac}, and run @code{./configure && make}, then @command{make} will *never* attempt to rebuilt @file{configure}, @file{Makefile.in}s, Lex or Yacc outputs, etc. I.e., this disables build rules for files which are usually distributed and that users should normally not have to update. If you run @code{./configure --enable-maintainer-mode}, then these rebuild rules will be active. People use @code{AM_MAINTAINER_MODE} either because they do want their users (or themselves) annoyed by timestamps lossage (@pxref{CVS}), or because they simply can't stand the rebuild rules and prefer running maintainer tools explicitly. @code{AM_MAINTAINER_MODE} also allows you to disable some custom build rules conditionally. Some developers use this feature to disable rules that need exotic tools that users may not have available. Several years ago Fran@,{c}ois Pinard pointed out several arguments against @code{AM_MAINTAINER_MODE}. Most of them relate to insecurity. By removing dependencies you get non-dependable builds: change to sources files can have no effect on generated files and this can be very confusing when unnoticed. He adds that security shouldn't be reserved to maintainers (what @code{--enable-maintainer-mode} suggests), on the contrary. If one user has to modify a @file{Makefile.am}, then either @file{Makefile.in} should be updated or a warning should be output (this is what Automake uses @code{missing} for) but the last thing you want is that nothing happens and the user doesn't notice it (this is what happens when rebuild rules are disabled by @code{AM_MAINTAINER_MODE}). Jim Meyering, the inventor of the @code{AM_MAINTAINER_MODE} macro was swayed by Fran@,{c}ois's arguments, and got rid of @code{AM_MAINTAINER_MODE} in all of his packages. Still many people continue to use @code{AM_MAINTAINER_MODE}, because it helps them working on projects where all files are kept under CVS, and because @command{missing} isn't enough if you have the wrong version of the tools. @node wildcards @section Why doesn't Automake support wildcards? @cindex wildcards Developers are lazy. They often would like to use wildcards in @file{Makefile.am}s, so they don't need to remember they have to update @file{Makefile.am}s every time they add, delete, or rename a file. There are several objections to this: @itemize @item When using CVS (or similar) developers need to remember they have to run @code{cvs add} or @code{cvs rm} anyway. Updating @file{Makefile.am} accordingly quickly becomes a reflex. Conversely, if your application doesn't compile because you forgot to add a file in @file{Makefile.am}, it will help you remember to @code{cvs add} it. @item Using wildcards makes easy to distribute files by mistake. For instance some code a developer is experimenting with (a test case, say) but which should not be part of the distribution. @item Using wildcards it's easy to omit some files by mistake. For instance one developer creates a new file, uses it at many places, but forget to commit it. Another developer then checkout the incomplete project and is able to run `make dist' successfully, even though a file is missing. @item Listing files, you control *exactly* what you distribute. If some file that should be distributed is missing from your tree, @code{make dist} will complain. Besides, you don't distribute more than what you listed. @item Finally it's really hard to @file{forget} adding a file to @file{Makefile.am}, because if you don't add it, it doesn't get compiled nor installed, so you can't even test it. @end itemize Still, these are philosophical objections, and as such you may disagree, or find enough value in wildcards to dismiss all of them. Before you start writing a patch against Automake to teach it about wildcards, let's see the main technical issue: portability. Although @code{$(wildcard ...)} works with GNU @command{make}, it is not portable to other @command{make} implementations. The only way Automake could support @command{$(wildcard ...)} is by expending @command{$(wildcard ...)} when @command{automake} is run. Resulting @file{Makefile.in}s would be portable since they would list all files and not use @code{$(wildcard ...)}. However that means developers need to remember they must run @code{automake} each time they add, delete, or rename files. Compared to editing @file{Makefile.am}, this is really little win. Sure, it's easier and faster to type @code{automake; make} than to type @code{emacs Makefile.am; make}. But nobody bothered enough to write a patch add support for this syntax. Some people use scripts to generated file lists in @file{Makefile.am} or in separate @file{Makefile} fragments. Even if you don't care about portability, and are tempted to use @code{$(wildcard ...)} anyway because you target only GNU Make, you should know there are many places where Automake need to know exactly which files should be processed. As Automake doesn't know how to expand @code{$(wildcard ...)}, you cannot use it in these places. @code{$(wildcard ...)} is a black box comparable to @code{AC_SUBST}ed variables as far Automake is concerned. You can get warnings about @code{$(wildcard ...}) constructs using the @code{-Wportability} flag. @node distcleancheck @section Files left in build directory after distclean @cindex distclean, diagnostic @cindex dependencies and distributed files @trindex distclean @trindex distcleancheck This is a diagnostic you might encounter while running @code{make distcheck}. As explained in @ref{Dist}, @code{make distcheck} attempts to build and check your package for errors like this one. @code{make distcheck} will perform a @code{VPATH} build of your package, and then call @code{make distclean}. Files left in the build directory after @code{make distclean} has run are listed after this error. This diagnostic really covers two kinds of errors: @itemize @bullet @item files that are forgotten by distclean; @item distributed files that are erroneously rebuilt. @end itemize The former left-over files are not distributed, so the fix is to mark them for cleaning (@pxref{Clean}), this is obvious and doesn't deserve more explanations. The latter bug is not always easy to understand and fix, so let's proceed with an example. Suppose our package contains a program for which we want to build a man page using @command{help2man}. GNU @command{help2man} produces simple manual pages from the @code{--help} and @code{--version} output of other commands (@pxref{Top, , Overview, help2man, The Help2man Manual}). Because we don't to force want our users to install @command{help2man}, we decide to distribute the generated man page using the following setup. @example # This Makefile.am is bogus. bin_PROGRAMS = foo foo_SOURCES = foo.c dist_man_MANS = foo.1 foo.1: foo$(EXEEXT) help2man --output=foo.1 ./foo$(EXEEXT) @end example This will effectively distribute the man page. However, @code{make distcheck} will fail with: @example ERROR: files left in build directory after distclean: ./foo.1 @end example Why was @file{foo.1} rebuilt? Because although distributed, @file{foo.1} depends on a non-distributed built file: @file{foo$(EXEEXT)}. @file{foo$(EXEEXT)} is built by the user, so it will always appear to be newer than the distributed @file{foo.1}. @code{make distcheck} caught an inconsistency in our package. Our intent was to distribute @file{foo.1} so users do not need installing @command{help2man}, however since this our rule causes this file to be always rebuilt, users @emph{do} need @command{help2man}. Either we should ensure that @file{foo.1} is not rebuilt by users, or there is no point in distributing @file{foo.1}. More generally, the rule is that distributed files should never depend on non-distributed built files. If you distribute something generated, distribute its sources. One way to fix the above example, while still distributing @file{foo.1} is to not depend on @file{foo$(EXEEXT)}. For instance, assuming @command{foo --version} and @command{foo --help} do not change unless @file{foo.c} or @file{configure.ac} change, we could write the following @file{Makefile.am}: @example bin_PROGRAMS = foo foo_SOURCES = foo.c dist_man_MANS = foo.1 foo.1: foo.c $(top_srcdir)/configure.ac $(MAKE) $(AM_MAKEFLAGS) foo$(EXEEXT) help2man --output=foo.1 ./foo$(EXEEXT) @end example This way, @file{foo.1} will not get rebuilt every time @file{foo$(EXEEXT)} changes. The @command{make} call makes sure @file{foo$(EXEEXT)} is up-to-date before @command{help2man}. Another way to ensure this would be to use separate directories for binaries and man pages, and set @code{SUBDIRS} so that binaries are built before man pages. We could also decide not to distribute @file{foo.1}. In this case it's fine to have @file{foo.1} dependent upon @file{foo$(EXEEXT)}, since both will have to be rebuilt. However it would be impossible to build the package in a cross-compilation, because building @file{foo.1} involves an @emph{execution} of @file{foo$(EXEEXT)}. Another context where such errors are common is when distributed files are built by tools which are built by the package. The pattern is similar: @example distributed-file: built-tools distributed-sources build-command @end example @noindent should be changed to @example distributed-file: distributed-sources $(MAKE) $(AM_MAKEFLAGS) built-tools build-command @end example @noindent or you could choose not to distribute @file{distributed-file}, if cross-compilation does not matter. The points made through these examples are worth a summary: @cartouche @itemize @item Distributed files should never depend upon non-distributed built files. @item Distributed files should be distributed will all their dependencies. @item If a file is @emph{intended} be rebuilt by users, there is no point in distributing it. @end itemize @end cartouche @vrindex distcleancheck_listfiles For desperate cases, it's always possible to disable this check by setting @code{distcleancheck_listfiles} as documented in @ref{Dist}. Make sure you do understand the reason why @code{make distcheck} complains before you do this. @code{distcleancheck_listfiles} is a way to @emph{hide} errors, not to fix them. You can always do better. @node renamed objects @section Why are object files sometimes renamed? This happens when per-target compilation flags are used. Object files need to be renamed just in case they would clash with object files compiled from the same sources, but with different flags. Consider the following example. @example bin_PROGRAMS = true false true_SOURCES = generic.c true_CPPFLAGS = -DEXIT_CODE=0 false_SOURCES = generic.c false_CPPFLAGS = -DEXIT_CODE=1 @end example @noindent Obviously the two programs are built from the same source, but it would be bad if they shared the same object, because @file{generic.o} cannot be built with both @code{-DEXIT_CODE=0} *and* @code{-DEXIT_CODE=1}. Therefore @command{automake} outputs rules to build two different objects: @file{true-generic.o} and @file{false-generic.o}. @command{automake} doesn't actually look whether sources files are shared to decide if it must rename objects. It will just rename all objects of a target as soon as it sees per-target compilation flags are used. It's OK to share object files when per-target compilation flags are not used. For instance @file{true} and @file{false} will both use @file{version.o} in the following example. @example AM_CPPFLAGS = -DVERSION=1.0 bin_PROGRAMS = true false true_SOURCES = true.c version.c false_SOURCES = false.c version.c @end example Note that the renaming of objects is also affected by the @code{_SHORTNAME} variable (@pxref{Program and Library Variables}). @node Multiple Outputs @section Handling Tools that Produce Many Outputs @cindex multiple outputs, rules with @cindex many outputs, rules with @cindex rules with multiple outputs This section describes a @command{make} idiom that can be used when a tool produces multiple output files. It is not specific to Automake and can be used in ordinary @file{Makefile}s. Suppose we have a program called @command{foo} that will read one file called @file{data.foo} and produce two files named @file{data.c} and @file{data.h}. We want to write a @file{Makefile} rule that captures this one-to-two dependency. The naive rule is incorrect: @example # This is incorrect. data.c data.h: data.foo foo data.foo @end example @noindent What the above rule really says is that @file{data.c} and @file{data.h} each depend on @file{data.foo}, and can each be built by running @code{foo data.foo}. In other words it is equivalent to: @example # We do not want this. data.c: data.foo foo data.foo data.h: data.foo foo data.foo @end example @noindent which means that @command{foo} can be run twice. Usually it will not be run twice, because @command{make} implementations are smart enough to check for the existence of the second file after the first one has been built; they will therefore detect that it already exists. However there are a few situations where it can run twice anyway: @itemize @item The most worrying case is when running a parallel @command{make}. If @file{data.c} and @file{data.h} are built in parallel, two @code{foo data.foo} commands will run concurrently. This is harmful. @item Another case is when the dependency (here @code{data.foo}) is (or depends upon) a phony target. @end itemize A solution that works with parallel @command{make} but not with phony dependencies is the following: @example data.c data.h: data.foo foo data.foo data.h: data.c @end example @noindent The above rules are equivalent to @example data.c: data.foo foo data.foo data.h: data.foo data.c foo data.foo @end example @noindent therefore a parallel @command{make} will have to serialize the builds of @file{data.c} and @file{data.h}, and will detect that the second is no longer needed once the first is over. Using this pattern is probably enough for most cases. However it does not scale easily to more output files (in this scheme all output files must be totally ordered by the dependency relation), so we will explore a more complicated solution. Another idea is to write the following: @example # There is still a problem with this one. data.c: data.foo foo data.foo data.h: data.c @end example @noindent The idea is that @code{foo data.foo} is run only when @file{data.c} needs to be updated, but we further state that @file{data.h} depends upon @file{data.c}. That way, if @file{data.h} is required and @file{data.foo} is out of date, the dependency on @file{data.c} will trigger the build. This is almost perfect, but suppose we have built @file{data.h} and @file{data.c}, and then we erase @file{data.h}. Then, running @code{make data.h} will not rebuild @file{data.h}. The above rules just state that @file{data.c} must be up-to-date with respect to @file{data.foo}, and this is already the case. What we need is a rule that forces a rebuild when @file{data.h} is missing. Here it is: @example data.c: data.foo foo data.foo data.h: data.c @@if test -f $@@; then :; else \ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi @end example The above scales easily to more outputs and more inputs. One of the output is picked up to serve as a witness of the run of the command, it depends upon all inputs, and all other outputs depend upon it. For instance if @command{foo} should additionally read @file{data.bar} and also produce @file{data.w} and @file{data.x}, we would write: @example data.c: data.foo data.bar foo data.foo data.bar data.h data.w data.x: data.c @@if test -f $@@; then :; else \ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi @end example There is still a minor problem with this setup. @command{foo} outputs four files, but we do not know in which order these files are created. Suppose that @file{data.h} is created before @file{data.c}. Then we have a weird situation. The next time @command{make} is run, @file{data.h} will appear older than @file{data.c}, the second rule will be triggered, a shell will be started to execute the @code{if...fi} command, but actually it will just execute the @code{then} branch, that is: nothing. In other words, because the witness we selected is not the first file created by @command{foo}, @command{make} will start a shell to do nothing each time it is run. A simple riposte is to fix the timestamps when this happens. @example data.c: data.foo data.bar foo data.foo data.bar data.h data.w data.x: data.c @@if test -f $@@; then \ touch $@@; \ else \ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi @end example Another solution, not incompatible with the previous one, is to use a different and dedicated file as witness, rather than using any of @command{foo}'s outputs. @example data.stamp: data.foo data.bar @@rm -f data.tmp @@touch data.tmp foo data.foo data.bar @@mv -f data.tmp $@@ data.c data.h data.w data.x: data.stamp @@if test -f $@@; then \ touch $@@; \ else \ rm -f data.stamp; \ $(MAKE) $(AM_MAKEFLAGS) data.stamp; \ fi @end example @file{data.tmp} is created before @command{foo} is run, so it has a timestamp older than output files output by @command{foo}. It is then renamed to @file{data.stamp} after @command{foo} has run, because we do not want to update @file{data.stamp} if @command{foo} fails. Using a dedicated witness like this is very handy when the list of output files is not known beforehand. As an illustration, consider the following rules to compile many @file{*.el} files into @file{*.elc} files in a single command. It does not matter how @code{ELFILES} is defined (as long as it is not empty: empty targets are not accepted by POSIX). @example ELFILES = one.el two.el three.el @dots{} ELCFILES = $(ELFILES:=c) elc-stamp: $(ELFILES) @@rm -f elc-temp @@touch elc-temp $(elisp_comp) $(ELFILES) @@mv -f elc-temp $@@ $(ELCFILES): elc-stamp @@if test -f $@@; then \ touch $@@; \ else \ rm -f elc-stamp; \ $(MAKE) $(AM_MAKEFLAGS) elc-stamp; \ fi @end example For completeness it should be noted that GNU @command{make} is able to express rules with multiple output files using pattern rules (@pxref{Pattern Examples, , Pattern Rule Examples, make, The GNU Make Manual}). We do not discuss pattern rules here because they are not portable, but they can be convenient in packages that assume GNU @command{make}. @c ========================================================== Appendices @page @node Copying This Manual @appendix Copying This Manual @menu * GNU Free Documentation License:: License for copying this manual @end menu @include fdl.texi @page @node Indices @appendix Indices @menu * Macro and Variable Index:: Index of Autoconf macros and Automake variables * General Index:: General index @end menu @node Macro and Variable Index @appendixsec Macro and Variable Index @printindex vr @node General Index @appendixsec General Index @printindex cp @page @contents @bye @c LocalWords: texinfo setfilename settitle setchapternewpage texi direntry @c LocalWords: dircategory in's aclocal ifinfo titlepage Tromey vskip pt sp @c LocalWords: filll defcodeindex ov cv op tr syncodeindex fn cp vr ifnottex @c LocalWords: dir Automake's ac Dist Gnits gnits cygnus dfn Autoconf's pxref @c LocalWords: cindex Autoconf autoconf perl samp cvs dist trindex SUBST foo @c LocalWords: xs emph FIXME ref vindex pkglibdir pkgincludedir pkgdatadir mt @c LocalWords: pkg libdir cvindex cpio bindir sbindir rmt pax sbin zar zardir @c LocalWords: HTML htmldir html noinst TEXINFOS nodist nobase strudel CFLAGS @c LocalWords: libmumble CC YFLAGS ansi knr itemx de fication config url comp @c LocalWords: depcomp elisp sh mdate mkinstalldirs mkdir py tex dvi ps pdf @c LocalWords: ylwrap zardoz INIT gettext acinclude mv FUNCS LIBOBJS LDADD fr @c LocalWords: uref featureful dnl src LINGUAS es ko nl pl sl sv PROG ISC doc @c LocalWords: POSIX STDC fcntl FUNC ALLOCA blksize struct stat intl po chmod @c LocalWords: ChangeLog SUBDIRS gettextize gpl testdata getopt INTLLIBS cpp @c LocalWords: localedir datadir DLOCALEDIR DEXIT CPPFLAGS autoreconf opindex @c LocalWords: AUX var symlink deps Wno Wnone package's aclocal's distclean @c LocalWords: ltmain xref LIBSOURCE LIBSOURCES LIBOBJ MEMCMP vs RANLIB CXX @c LocalWords: LDFLAGS LIBTOOL libtool XTRA LIBS gettext's acdir APIVERSION @c LocalWords: dirlist noindent usr MULTILIB multilib Multilibs TIOCGWINSZ sc @c LocalWords: GWINSZ termios SRCDIR tarball bzip LISPDIR lispdir XEmacs CCAS @c LocalWords: emacsen MicroEmacs CCASFLAGS UX GCJ gcj GCJFLAGS posix DMALLOC @c LocalWords: dmalloc ldmalloc REGEX regex rx DEPDIR DEP DEFUN aclocaldir fi @c LocalWords: mymacro myothermacro AMFLAGS autopoint autogen libtoolize yum @c LocalWords: autoheader README MAKEFLAGS subdir Inetutils sync COND endif @c LocalWords: Miller's installable includedir inc pkgdata EXEEXT libexec bsd @c LocalWords: pkglib libexecdir prog libcpio cpio's dlopen dlpreopen linux @c LocalWords: subsubsection OBJEXT esac lib LTLIBRARIES liblob LIBADD AR ar @c LocalWords: ARFLAGS cru ing maude libgettext lo LTLIBOBJS rpath SGI PRE yy @c LocalWords: libmaude CCLD CXXFLAGS FFLAGS LFLAGS OBJCFLAGS RFLAGS DEFS cc @c LocalWords: SHORTNAME vtable srcdir nostdinc basename yxx cxx ll lxx gdb @c LocalWords: lexers yymaxdepth maxdepth yyparse yylex yyerror yylval lval @c LocalWords: yychar yydebug yypact yyr yydef def yychk chk yypgo pgo yyact @c LocalWords: yyexca exca yyerrflag errflag yynerrs nerrs yyps yypv pv yys @c LocalWords: yystate yytmp tmp yyv yyval val yylloc lloc yyreds yytoks toks @c LocalWords: yylhs yylen yydefred yydgoto yysindex yyrindex yygindex yyname @c LocalWords: yytable yycheck yyrule byacc CXXCOMPILE CXXLINK FLINK cfortran @c LocalWords: Catalogue preprocessable FLIBS libfoo baz JAVACFLAGS java exe @c LocalWords: SunOS fying basenames exeext uninstalled oldinclude kr FSF's @c LocalWords: pkginclude oldincludedir sysconf sharedstate localstate gcc rm @c LocalWords: sysconfdir sharedstatedir localstatedir preexist CLEANFILES gz @c LocalWords: unnumberedsubsec depfile tmpdepfile depmode const interoperate @c LocalWords: JAVAC javac JAVAROOT builddir CLASSPATH ENV pyc pyo pkgpython @c LocalWords: pyexecdir pkgpyexecdir Python's pythondir pkgpythondir txi ois @c LocalWords: installinfo vers MAKEINFO makeinfo MAKEINFOFLAGS noinstall rf @c LocalWords: mandir thesame alsothesame installman myexecbin DESTDIR Pinard @c LocalWords: uninstall installdirs uninstalls MOSTLYCLEANFILES mostlyclean @c LocalWords: DISTCLEANFILES MAINTAINERCLEANFILES gzip'd GZIP gzip shar exp @c LocalWords: distdir distcheck distcleancheck listfiles distuninstallcheck @c LocalWords: VPATH tarfile stdout XFAIL DejaGnu dejagnu DEJATOOL runtest ln @c LocalWords: RUNTESTDEFAULTFLAGS toolchain RUNTESTFLAGS asis readme DVIPS @c LocalWords: installcheck gzipped tarZ std utils etags mkid multilibbing cd @c LocalWords: ARGS taggable ETAGSFLAGS lang ctags CTAGSFLAGS GTAGS gtags idl @c LocalWords: foocc doit idlC multilibs ABIs cmindex defmac ARG enableval @c LocalWords: MSG xtrue DBG pathchk CYGWIN afile proglink versioned CVS's @c LocalWords: wildcards Autoconfiscated subsubheading autotools Meyering API @c LocalWords: ois's wildcard Wportability cartouche vrindex printindex Duret @c LocalWords: DSOMEFLAG DVERSION automake Lutz insertcopying versioning FAQ @c LocalWords: LTLIBOBJ Libtool's libtool's libltdl dlopening itutions libbar @c LocalWords: WANTEDLIBS libhello sublibraries libtop libsub dlopened Ratfor @c LocalWords: mymodule timestamps timestamp underquoted MAKEINFOHTMLFLAGS @c LocalWords: GNUmakefile buildir Subpackages subpackage's subpackages