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Python Program to Replace Specific Line in File

  • Last Updated : 14 Sep, 2021
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In this article, we are going to write a Python program to replace specific lines in the file.

We will first open the file in read-only mode and read all the lines using readlines(), creating a list of lines storing it in a variable. We will make the necessary changes to a specific line and after that, we open the file in write-only mode and write the modified data using writelines().

File for demonstration:

Explanation:

First, open the File in read-only mode and read the file line by line using readlines() method, and store it in a variable.



with open('example.txt','r',encoding='utf-8') as file:
    data = file.readlines()

The variable will contain a list of lines, Printing it will show all the lines present inside the list.

print(data)

Make necessary changes to a specific line. (Here, I have modified the second line)

data[1] = "Here is my modified Line 2\n"

Open the file again in write-only mode and write the modified data using writelines() method.

With open('example.txt', 'w', encoding='utf-8') as file:
    file.writelines(data)

Below is the implementation:

Python3




with open('example.txt', 'r', encoding='utf-8') as file:
    data = file.readlines()
  
print(data)
data[1] = "Here is my modified Line 2\n"
  
with open('example.txt', 'w', encoding='utf-8') as file:
    file.writelines(data)

Output:

['Line 1\n', 'Here is my modified Line 2\n', 'Line 3']

After Modification:

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