Make知识点总结， 有时间再补充些自己比较困惑的点

为什么使用make

1、包含多个源文件的项目在编译时有长而复杂的命令行，可以通过makefile保存这些命令行来简化该工作 2、make可以减少重新编译所需要的时间，因为make可以识别出哪些文件是新修改的 3、Make维护了当前项目中各文件的相关关系，从而可以在编译前检查是否可以找到所有的文件

自己也用了很久的make, 以上回答的这3点我也都知道， 可是从来没有系统的写下来总结过， 感谢Make面试题

Special Built-in Target Names

Certain names have special meanings if they appear as targets.Special-Targets

.PHONY

The prerequisites of the special target .PHONY are considered to be phony targets. When it is time to consider such a target, make will run its recipe unconditionally, regardless of whether a file with that name exists or what its last-modification time is. See Phony Targets.

.PHONY: clean
clean:
        rm *.o temp

Once this is done, ‘make clean’ will run the recipe regardless of whether there is a file named clean.

.SUFFIXES

后缀自定义规则， 定义某一类型的文件的处理规则

compiler flag

Use the LIBADD primary for libraries, and LDADD for executables. If you were building a libtool library libfoo.la, that depended on another library libbar.la, you would use:

libfoo_la_LIBADD = libbar.la

If you had other non-libtool libraries, you would also add these with -L and -l options:

libfoo_la_LIBADD = libbar.la -L/opt/local/lib -lpng

Typically, you would use the configure script to find these extra libraries, and use AC_SUBST to pass them with:

libfoo_la_LIBADD = libbar.la $(EXTRA_FOO_LIBS)

For a program, just use LDADD :

myprog_LDADD = libfoo.la # links libfoo, libbar, and libpng to myprog.

Sometimes the boundaries are a bit vague. $(EXTRA_FOO_LIBS) could have been added to myprog_LDADD. Adding dependencies to a libtool (.la) library, and using libtool do all the platform-specific linker magic, is usually the best approach. It keeps all the linker metadata in the one place.

AutoMake tools

See demo project