多级目录中的Makefile

以下示例演示了如何在多级目录下维护多个Makefile，以使每级目录都可单独支持'make'命令。

目录结构：

[user@localhost maketest]$ tree

.

|-- Makefile --- Makefile 1

|-- subdir1

|   `-- Makefile --- Makefile 2

`-- subdir2

    |-- Makefile --- Makefile 3

    `-- test.cpp

Makefile 1:

SUBDIRS = subdir1 subdir2

.PHONY: default all clean $(SUBDIRS)

default: all

all clean:

#   this 'make' cmd will cause the Makefile be read again by 'make'

    $(MAKE) $(SUBDIRS) TARGET=$@

$(SUBDIRS): print

    $(MAKE) -C $@ $(TARGET)

print:

    @echo "--- MAKE  =$(MAKE)"

    @echo "--- TARGET=$(TARGET)"

Makefile 2:

.PHONY: all clean

all:

    @echo "----- make all in subdir1"

    @echo "----- current dir is: $(PWD)"

    @echo "----- current time is: $(shell date)"

clean:

    @echo "----- make clean in subdir1"

Makefile 3:

CXX     = g++

BIN     = test.exe

OBJS    = test.o

LDLIBS += -lstdc++

.PHONY: all clean print_all

all: print_all $(BIN)

print_all:

    @echo "----- make all in subdir2 -----"

$(BIN): $(OBJS)

    $(CXX) $(OBJS) -o $@ $(LDLIBS)

%.o: %.cpp

    $(CXX) -c $<

clean:

    @echo "----- make clean in subdir2 -----"

    rm -f $(BIN) $(OBJS)

test.cpp:

#include <iostream>

using namespace std;

int main(void)

{

    cout << __FILE__ << "," << __LINE__ << endl;

    return 0;

}

Output of ‘make’：

[user@localhost maketest]$ make

make subdir1 subdir2 TARGET=all

make[1]: Entering directory `/home/user/maketest'

--- MAKE  =make

--- TARGET=all

make -C subdir1 all

make[2]: Entering directory `/home/user/maketest/subdir1'

----- make all in subdir1

----- current dir is: /home/user/maketest

----- current time is: Sun Mar 13 16:14:43 CST 2011

make[2]: Leaving directory `/home/user/maketest/subdir1'

make -C subdir2 all

make[2]: Entering directory `/home/user/maketest/subdir2'

----- make all in subdir2 -----

g++ -c test.cpp

g++ test.o -o test.exe -lstdc++

make[2]: Leaving directory `/home/user/maketest/subdir2'

make[1]: Leaving directory `/home/user/maketest'

Output of ‘make clean’:

[user@localhost maketest]$ make clean

make subdir1 subdir2 TARGET=clean

make[1]: Entering directory `/home/user/maketest'

--- MAKE  =make

--- TARGET=clean

make -C subdir1 clean

make[2]: Entering directory `/home/user/maketest/subdir1'

----- make clean in subdir1

make[2]: Leaving directory `/home/user/maketest/subdir1'

make -C subdir2 clean

make[2]: Entering directory `/home/user/maketest/subdir2'

----- make clean in subdir2 -----

rm -f test.exe test.o

make[2]: Leaving directory `/home/user/maketest/subdir2'

make[1]: Leaving directory `/home/user/maketest'