How to delete from a text file, all lines that contain a specific string?

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To delete all lines from a text file that contain a specific string, you can use a scripting or programming language like Python. Below is an example using Python to achieve this:

python
# Define the string you want to search for and remove
string_to_remove = "specific_string"

# Open the input file in read mode
with open("input.txt", "r") as infile:
    # Read all lines from the input file into a list
    lines = infile.readlines()

# Open the same file in write mode to overwrite its contents
with open("input.txt", "w") as outfile:
    # Iterate through the lines and write only the lines that do not contain the specified string
    for line in lines:
        if string_to_remove not in line:
            outfile.write(line)

In this example, replace "specific_string" with the actual string you want to remove from the text file, and "input.txt" with the path to your input text file.

Here's a step-by-step explanation of the code:

  1. Define the string_to_remove variable to store the string you want to delete from the text file.

  2. Open the input file "input.txt" in read mode using a with statement to ensure it's properly closed after reading.

  3. Read all the lines from the input file into a list called lines.

  4. Open the same file "input.txt" in write mode to overwrite its contents, again using a with statement.

  5. Iterate through the lines in the lines list, and for each line, check if string_to_remove is not in the line. If it's not in the line, write that line to the output file.

After running this script, all lines containing the specified string will be removed from the text file. The original file will be overwritten with the modified content. Make sure to create a backup of your file before running such operations to avoid data loss if needed.

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