如何在makefile中执行此操作？

Here is my makefile :

这是我的makefile:

BIN = ../mylib.a
CXX = g++5
CFLAGS  = -O2 -pipe -mtune=i686 -g
#################################



default:
    @echo 'Compiling socket' ;       $(CXX) $(CFLAGS) -c socket.c
    @echo 'Compiling fdwatch';       $(CXX) $(CFLAGS) -c fdwatch.c
    @echo 'Compiling signal' ;       $(CXX) $(CFLAGS) -c signal.c
    @echo 'Compiling heart'  ;       $(CXX) $(CFLAGS) -c heart.c

    @echo 'Create library static';    ar cru $(BIN) *.o
    @echo 'Compiling';                ranlib $(BIN)
    @echo 'Delete .obj files';        rm -f *.o
BIN = .