python3实现shell的sed的功能

#/usr/bin/env python
#yehui

import os, sys

'''

try:                                                                                                               
    os.mkdir('userinfo')
except FileExistsError:
    print("文件夹已存在跳过")

'''

####判断对应目录是否存在

class PathJudge:

    def __init__(self):
        self.path1 = "userinfo"
        self.path2 = "user_dict_info"

    def judge_path(self):
        if os.path.exists('userinfo'):
            print("file %s is exists and then pass" % self.path1)
        else:
            os.mkdir(self.path1)
        if os.path.exists('user_dict_info'):
            print("file %s is exists and then pass" % self.path2)
        else:
            os.mkdir(self.path2)

class Sed:

    def __init__(self, oldstr, newstr):              ###定义替换sed
        self.old_file = oldstr                       ###旧内容
        self.new_file = newstr                       ###新内容
        self.file_path = "userinfo/clock"            ###创建目录变量

    def sedfile(self):
        with open(self.file_path, 'r') as self.f, open("userinfo/back", "a+") as self.f1:   ##同时打需要修改的文件,及新创建新内容的文件
            for self.i in self.f:
                if self.old_file in self.i:
                    self.i = self.i.replace(self.old_file, self.new_file)    ##对内容进行替换操作
                self.f1.write(self.i)  ##写入操作
                self.f1.flush()    ##立即刷新
        os.remove(self.file_path)  ##删除原文件
        os.rename("userinfo/back", self.file_path)  ##新文件改名

 

if __name__ == '__main__':

　　sed = Sed("0这是坚强的肥DD!", "我去!!!")
　　sed.sedfile()