Python文件操作中进行字符串替换的方法（保存到新文件/当前文件）

题目：

1.首先将文件：/etc/selinux/config 进行备份 文件名为 /etc/selinux/config.bak

2.再文件：/etc/selinux/config 中的enforcing 替换为 disabled

# This file controls the state of SELinux on the system.
# SELINUX= can take one of these three values:
#   enforcing - SELinux security policy is enforced.
#   permissive - SELinux prints warnings instead of enforcing.
#   disabled - No SELinux policy is loaded.
SELINUX=disabled
# SELINUXTYPE= can take one of three two values:
#   targeted - Targeted processes are protected,
#   minimum - Modification of targeted policy. Only selected processes are protected. 
#   mls - Multi Level Security protection.
SELINUXTYPE=enforcing

•方法一：用replace

import os
import shutil
def selinux_config():
  """
  关闭SELINUX
  修改文件内容
  :return:
  """
  file_selinux = '/etc/selinux/config'
  backup_file_selinux = file_selinux + '.bak'
  temp_file_selinux = file_selinux + '.temp'
  if not os.path.exists(backup_file_selinux):
    shutil.copy2(file_selinux, backup_file_selinux)
    with open(file_selinux, mode='r') as fr, open(temp_file_selinux, mode='w') as fw:
      origin_line = 'SELINUX=enforcing'
      update_line = 'SELINUX=disabled'
      for line in fr:
        fw.write(line.replace(origin_line, update_line))
    os.remove(file_selinux)
    os.rename(temp_file_selinux, file_selinux)
if __name__ == '__main__':
  selinux_config()

•方法二：用re.sub

#! /usr/bin/env python
# -*- coding: utf-8 -*-
import os
import re
import shutil
def selinux_config():
  """
  关闭SELINUX
  修改文件内容
  :return:
  """
  file_selinux = '/etc/selinux/config'
  backup_file_selinux = file_selinux + '.bak'
  temp_file_selinux = file_selinux + '.temp'
  if not os.path.exists(backup_file_selinux):
    shutil.copy2(file_selinux, backup_file_selinux)
    with open(file_selinux, mode='r') as fr, open(temp_file_selinux, mode='w') as fw:
      origin_line = 'SELINUX=enforcing'
      update_line = 'SELINUX=disabled'
      for line in fr:
        re_sub_list = re.sub(origin_line, update_line, line) # 这里用re.sub进行替换后放入 re_sub_list中
        fw.writelines(re_sub_list) # 将列表中的每一行进行写入。writelines是将序列对象中的每一行进行写入。
    os.remove(file_selinux)
    os.rename(temp_file_selinux, file_selinux)
if __name__ == '__main__':
  selinux_config()

总结

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