# 声明如下目标是伪目标
.PHONY: all install clean distclean

all: hello  # 编译最终目标

hello : hello.o
	gcc -o hello hello.o

hello.o : hello.c
	gcc -o hello.o -c hello.c

install:  # 安装程序
	cp hello /usr/local/bin/

clean:  # 清除目标文件
	rm hello.o

distclean:  # 恢复成源码状态
	rm hello.o hello