Configure，Makefile.am, Makefile.in, Makefile文件之间关系

1.autoscan (autoconf): 扫描源代码以搜寻普通的可移植性问题，比如检查编译器，库，头文件等，生成文件configure.scan,它是configure.ac的一个雏形。

your source files --> [autoscan*] --> [configure.scan] --> configure.ac
2.aclocal (automake):根据已经安装的宏，用户定义宏和acinclude.m4文件中的宏将configure.ac文件所需要的宏集中定义到文件 aclocal.m4中。aclocal是一个perl 脚本程序，它的定义是：“aclocal - create aclocal.m4 by scanning configure.ac”

user input files   optional input     process          output files
================   ==============     =======          ============

acinclude.m4 - - - - -.
V
.-------,
configure.ac ------------------------>|aclocal|
{user macro files} ->|       |------> aclocal.m4
`-------'
3.autoheader(autoconf): 根据configure.ac中的某些宏，比如cpp宏定义，运行m4，声称config.h.in

user input files    optional input     process          output files
================    ==============     =======          ============

aclocal.m4 - - - - - - - .
|
V
.----------,
configure.ac ----------------------->|autoheader|----> autoconfig.h.in
`----------'

4.automake: automake将Makefile.am中定义的结构建立Makefile.in，然后configure脚本将生成的Makefile.in文件转换 为Makefile。如果在configure.ac中定义了一些特殊的宏，比如AC_PROG_LIBTOOL，它会调用libtoolize，否则它 会自己产生config.guess和config.sub

user input files   optional input   processes          output files
================   ==============   =========          ============

.--------,
|        | - - -> COPYING
|        | - - -> INSTALL
|        |------> install-sh
|        |------> missing
|automake|------> mkinstalldirs
configure.ac ----------------------->|        |
Makefile.am  ----------------------->|        |------> Makefile.in
|        |------> stamp-h.in
.---+        | - - -> config.guess
|   |        | - - -> config.sub
|   `------+-'
|          | - - - -> config.guess
|libtoolize| - - - -> config.sub
|          |--------> ltmain.sh
|          |--------> ltconfig
`----------'

5.autoconf:将configure.ac中的宏展开，生成configure脚本。这个过程可能要用到aclocal.m4中定义的宏。

user input files   optional input   processes          output files
================   ==============   =========          ============

aclocal.m4 ,autoconfig.h.in - - - - - - -.
V
.--------,
configure.ac ----------------------->|autoconf|------> configure

6. ./configure的过程

.-------------> [config.cache]
configure* --------------------------+-------------> config.log
|
[config.h.in] -.            v            .--> [autoconfig.h]
+-------> config.status* -+
Makefile.in ---'                         `-->   Makefile

7. make过程

[autoconfig.h] -.
+--> make* --->  程序
Makefile   ---'

.---------,
config.site - - ->|         |
config.cache - - ->|configure| - - -> config.cache
|         +-,
`-+-------' |
|         |----> config.status
config.h.in ------->|config-  |----> config.h
Makefile.in ------->|  .status|----> Makefile
|         |----> stamp-h
|         +--,
.-+         |  |
| `------+--'  |
ltmain.sh ------->|ltconfig|-------> libtool
|        |     |
`-+------'     |
|config.guess|
| config.sub |
`------------'

[code=plain].--------,
Makefile ------>|        |
config.h ------>| make |
{project sources} ---------------->|        |--------> {project targets}
.-+        +--,
| `--------'  |
|   libtool   |
|   missing   |
|  install-sh |
|mkinstalldirs|
`-------------'

实例
：

在/hello/目录下创建一个hello.c文件，并编译运行它：
#cd /hello/
(1) 编写源文件hello.c：
#include<stdio.h>
int main(int argc, char** argv)
{
printf("Hello, GNU!n");
return 0;
}
[litao@vm0000131 hello]$ ll
total 4
-rw-rw-r-- 1 litao litao 68 Aug 12 12:02 hello.c
一、autoscan
[litao@vm0000131 hello]$ autoscan
autom4te: configure.ac: no such file or directory
autoscan: /usr/bin/autom4te failed with exit status: 1
[litao@vm0000131 hello]$ ll
total 8
-rw-rw-r-- 1 litao litao 0 Aug 12 12:03 autoscan.log
-rw-rw-r-- 1 litao litao 457 Aug 12 12:03 configure.scan
-rw-rw-r-- 1 litao litao 68 Aug 12 12:02 hello.c
已经生成了configure.scan，autoscan.log文件
将configure.scan 修改为 configure.in，最后修改的内容如下：
[litao@vm0000131 hello]$ mv configure.scan configure.in
[litao@vm0000131 hello]$ vim configure.in

# -*- Autoconf -*-
# Process this file with autoconf to produce a configure script.

AC_PREREQ(2.59)
AC_INIT(FULL-PACKAGE-NAME, VERSION, BUG-REPORT-ADDRESS)
AC_CONFIG_SRCDIR([hello.c])
#AC_CONFIG_HEADER([config.h])
AM_INIT_AUTOMAKE(hello, 1.0)
# Checks for programs.
AC_PROG_CC

# Checks for libraries.

# Checks for header files.

# Checks for typedefs, structures, and compiler characteristics.

# Checks for library functions.
AC_OUTPUT(Makefile)
二、acloacl

[litao@vm0000131 hello]$ aclocal

生成 aclocal.m4 和 autom4te.cache (生成aclocal.m4的过程中涉及到configure.in)
[litao@vm0000131 hello]$ ll
total 44
-rw-rw-r-- 1 litao litao 31120 Aug 12 12:08 aclocal.m4
drwxr-xr-x 2 litao litao 4096 Aug 12 12:08 autom4te.cache
-rw-rw-r-- 1 litao litao 0 Aug 12 12:03 autoscan.log
-rw-rw-r-- 1 litao litao 496 Aug 12 12:08 configure.in
-rw-rw-r-- 1 litao litao 68 Aug 12 12:02 hello.c
三、antoconf

[litao@vm0000131 hello]$ autoconf
生成 configure (根据 configure.in, 和 aclocal.m4)

[litao@vm0000131 hello]$ ll

total 168

-rw-rw-r-- 1 litao litao 31120 Aug 12 12:08 aclocal.m4

drwxr-xr-x 2 litao litao 4096 Aug 12 12:11 autom4te.cache

-rw-rw-r-- 1 litao litao 0 Aug 12 12:03 autoscan.log

-rwxrwxr-x 1 litao litao 122297 Aug 12 12:11 configure

-rw-rw-r-- 1 litao litao 496 Aug 12 12:08 configure.in

-rw-rw-r-- 1 litao litao 68 Aug 12 12:02 hello.c

四、编写Makefile.am：
AUTOMAKE_OPTIONS= foreign
bin_PROGRAMS= hello
hello_SOURCES= hello.c
五、automake
生成 Makefile.in， depcomp， install-sh， 和 missing (根据 Makefile.am, 和 aclocal.m4)
[litao@vm0000131 hello]$ automake
configure.in: required file `./install-sh' not found
configure.in: required file `./missing' not found
Makefile.am: required file `./depcomp' not found
[litao@vm0000131 hello]$ automake --add-missing
configure.in: installing `./install-sh'
configure.in: installing `./missing'
Makefile.am: installing `./depcomp'
[litao@vm0000131 hello]$ ll
total 192
-rw-rw-r-- 1 litao litao 31120 Aug 12 12:08 aclocal.m4
drwxr-xr-x 2 litao litao 4096 Aug 12 12:14 autom4te.cache
-rw-rw-r-- 1 litao litao 0 Aug 12 12:03 autoscan.log
-rwxrwxr-x 1 litao litao 122297 Aug 12 12:11 configure
-rw-rw-r-- 1 litao litao 496 Aug 12 12:08 configure.in
lrwxrwxrwx 1 litao litao 31 Aug 12 12:16 depcomp -> /usr/share/automake-1.9/depcomp
-rw-rw-r-- 1 litao litao 68 Aug 12 12:02 hello.c
lrwxrwxrwx 1 litao litao 34 Aug 12 12:16 install-sh -> /usr/share/automake-1.9/install-sh
-rw-rw-r-- 1 litao litao 69 Aug 12 12:15 Makefile.am
-rw-rw-r-- 1 litao litao 16561 Aug 12 12:16 Makefile.in
lrwxrwxrwx 1 litao litao 31 Aug 12 12:16 missing -> /usr/share/automake-1.9/missing
六、configure
生成 Makefile， config.log， 和 config.status