mkdir -p with open

mkdir -p 递归的创建子目录 比如 mkdir -p testA/testB

with open('dir','r') as f: 自动的管理文件对象的打开和关闭

打开多个文件

with open('dir1','r') as f1:

    with open('dir2','r') as f2:

        with open('dir3','r') as f3:

            ......