5. Creating a ‘Makefile.in’

To create all the ‘Makefile.in’s for a package, run the automake program in the top level directory, with no arguments. automake will automatically find each appropriate ‘Makefile.am’ (by scanning ‘configure.ac’; see section Scanning ‘configure.ac’) and generate the corresponding ‘Makefile.in’. Note that automake has a rather simplistic view of what constitutes a package; it assumes that a package has only one ‘configure.ac’, at the top. If your package has multiple ‘configure.ac’s, then you must run automake in each directory holding a ‘configure.ac’. (Alternatively, you may rely on Autoconf's autoreconf, which is able to recurse your package tree and run automake where appropriate.)

You can optionally give automake an argument; ‘.am’ is appended to the argument and the result is used as the name of the input file. This feature is generally only used to automatically rebuild an out-of-date ‘Makefile.in’. Note that automake must always be run from the topmost directory of a project, even if being used to regenerate the ‘Makefile.in’ in some subdirectory. This is necessary because automake must scan ‘configure.ac’, and because automake uses the knowledge that a ‘Makefile.in’ is in a subdirectory to change its behavior in some cases.

Automake will run autoconf to scan ‘configure.ac’ and its dependencies (i.e., ‘aclocal.m4’ and any included file), therefore autoconf must be in your PATH. If there is an AUTOCONF variable in your environment it will be used instead of autoconf, this allows you to select a particular version of Autoconf. By the way, don't misunderstand this paragraph: automake runs autoconf to scan your ‘configure.ac’, this won't build ‘configure’ and you still have to run autoconf yourself for this purpose.

automake accepts the following options:

-a

--add-missing

Automake requires certain common files to exist in certain situations; for instance, ‘config.guess’ is required if ‘configure.ac’ invokes AC_CANONICAL_HOST. Automake is distributed with several of these files (see section Programs automake might require); this option will cause the missing ones to be automatically added to the package, whenever possible. In general if Automake tells you a file is missing, try using this option. By default Automake tries to make a symbolic link pointing to its own copy of the missing file; this can be changed with ‘--copy’.

Many of the potentially-missing files are common scripts whose location may be specified via the AC_CONFIG_AUX_DIR macro. Therefore, AC_CONFIG_AUX_DIR's setting affects whether a file is considered missing, and where the missing file is added (see section Other things Automake recognizes).

In some strictness modes, additional files are installed, see The effect of ‘--gnu’ and ‘--gnits’ for more information.

--libdir=dir

Look for Automake data files in directory dir instead of in the installation directory. This is typically used for debugging.

-c

--copy

When used with ‘--add-missing’, causes installed files to be copied. The default is to make a symbolic link.

--cygnus

Causes the generated ‘Makefile.in’s to follow Cygnus rules, instead of GNU or Gnits rules. For more information, see The effect of ‘--cygnus’.

-f

--force-missing

When used with ‘--add-missing’, causes standard files to be reinstalled even if they already exist in the source tree. This involves removing the file from the source tree before creating the new symlink (or, with ‘--copy’, copying the new file).

--foreign

Set the global strictness to ‘foreign’. For more information, see Strictness.

--gnits

Set the global strictness to ‘gnits’. For more information, see The effect of ‘--gnu’ and ‘--gnits’.

--gnu

Set the global strictness to ‘gnu’. For more information, see The effect of ‘--gnu’ and ‘--gnits’. This is the default strictness.

--help

Print a summary of the command line options and exit.

-i

--ignore-deps

This disables the dependency tracking feature in generated ‘Makefile’s; see Automatic dependency tracking.

--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.

--no-force

Ordinarily automake creates all ‘Makefile.in’s mentioned in ‘configure.ac’. This option causes it to only update those ‘Makefile.in’s that are out of date with respect to one of their dependents.

-o dir

--output-dir=dir

Put the generated ‘Makefile.in’ in the directory dir. Ordinarily each ‘Makefile.in’ is created in the directory of the corresponding ‘Makefile.am’. This option is deprecated and will be removed in a future release.

-v

--verbose

Cause Automake to print information about which files are being read or created.

--version

Print the version number of Automake and exit.

-W CATEGORY

--warnings=category

Output warnings falling in category. category can be one of:

gnu

warnings related to the GNU Coding Standards (see (standards)Top section `Top' in The GNU Coding Standards).

obsolete

obsolete features or constructions

override

user redefinitions of Automake rules or variables

portability

portability issues (e.g., use of make features that are known to be not portable)

syntax

weird syntax, unused variables, typos

unsupported

unsupported or incomplete features

all

all the warnings

none

turn off all the warnings

error

treat warnings as errors

A category can be turned off by prefixing its name with ‘no-’. For instance, ‘-Wno-syntax’ will hide the warnings about unused variables.

The categories output by default are ‘syntax’ and ‘unsupported’. Additionally, ‘gnu’ and ‘portability’ are enabled in ‘--gnu’ and ‘--gnits’ strictness. On the other hand, the ‘silent-rules’ options (see section Changing Automake's Behavior) turns off portability warnings about recursive variable expansions.

The environment variable WARNINGS can contain a comma separated list of categories to enable. It will be taken into account before the command-line switches, this way ‘-Wnone’ will also ignore any warning category enabled by WARNINGS. This variable is also used by other tools like autoconf; unknown categories are ignored for this reason.

If the environment variable AUTOMAKE_JOBS contains a positive number, it is taken as the maximum number of Perl threads to use in automake for generating multiple ‘Makefile.in’ files concurrently. This is an experimental feature.