GNU Automake 版本(version 1.16.1, 26 February 2018)
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5 创建一个 Makefile.in
为了创建一个包的Makefile.in，只需要在顶层目录执行命令 automake即可。 automake 会通过扫描文件configure.ac来找到每一个 Makefile.am 并生成相应的Makefile.in。
此处留意：
automake假定一个包只有一个configure.ac，所以如果你的包包含多个configure.ac就需要在每个包含的目录执行automake，或者使用Autoconf的命令autoreconf，这个命令可以自动遍历所有的目录。
另外还需要留意 automake 必须在顶层目录执行，顶层目录需要包含文件 configure.ac。
Automake通过运行autoconf来扫描文件 configure.ac及它的依赖，因此autoconf 必须在你的环境变量里面，如果有另外一个 AUTOCONF 环境变量，那么就会 替代默认的 autoconf，这在使用另外一个版本的时候比较有用。
注：
automake只是通过autoconf来扫描configure.ac，并不会构建configure，所以还需要使用autoconf来构建。
automake 接收下面的参数：
-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 (; 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 (.
In some strictness modes, additional files are installed, x
--libdir=DIR
Look for Automake data files in directory DIR instead of in the
installation directory. This is typically used for debugging.
The environment variable `AUTOMAKE_LIBDIR` provides another way to
set the directory containing Automake data files. However
`--libdir` takes precedence over it.
--print-libdir
Print the path of the installation directory containing
Automake-provided scripts and data files (like e.g., texinfo.texi
and install-sh).
-c--copy
使用 --add-missing的时候默认会生成一个符号链接，这个选项会拷贝文件。
-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
设定级别为 foreign.
--gnits
设定级别为 gnits.
--gnu
设定级别为 gnu.
--help
打印一系列命令行选项并退出
-i--ignore-deps
This disables the dependency tracking feature in generated
Makefiles; see
--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.ins mentioned in
configure.ac. This option causes it to only update those
Makefile.ins 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
打印版本号并退出
-W CATEGORY--warnings=CATEGORY
Output warnings falling in CATEGORY. CATEGORY can be one of:
gnu
warnings related to 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)
extra-portability
extra portability issues related to obscure tools. One
example of such a tool is the Microsoft lib archiver.
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 categorie output by default are `obsolete`, `syntax` and
`unsupported`. Additionally, `gnu` and `portability` are enabled
in `--gnu` and `--gnits` strictness.
Turning off `portability` will also turn off `extra-portability`,
and similarly turning on `extra-portability` will also turn on
`portability`. However, turning on `portability` or turning off
`extra-portability` will not affect the other category.
The environment variable `WARNINGS` can contain a comma separated
list of categorie 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 categorie 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 inautomake for generating multiple Makefile.in files concurrently.
This is an experimental feature.
