Python修改文件方法——字符串替换

#字符串替换
import sys
f = open("yesterday2","r",encoding="utf-8")
f_new = open("yesterday2.bak","w",encoding="utf-8")

find_str = sys.argv[1]
replace_str = sys.argv[2]
for line in f:
    if find_str in line:
        line = line.replace(find_str,replace_str)
    f_new.write(line)
f.close()
f_new.close()

#with执行问了，文件就自动关闭了！ 开发规范一行代码不能超过80字符： \

with open("yesterday2","r",encoding="utf-8") as f ,\   
      open("yesterday2", "r", encoding="utf-8") as f2:
    for line in f:
        print(line)