Python遍历文件

import os

s = os.sep
root = "d:" + s + "ll" + s 

for rt, dirs, files in os.walk(root):
    for f in files:
        fname = os.path.splitext(f)
        new = fname[0] + 'b' + fname[1]
        os.rename(os.path.join(rt,f),os.path.join(rt,new))