How to Replace all instances of a string in a file?

1. Open the file in read mode using the open() function.
2. Read the contents of the file into a string using the read() method.
3. Use the replace() method to replace all instances of the target string with the new string.
4. Open the file in write mode using the open() function.
5. Write the modified string to the file using the write() method.
6. Close the file using the close() method.

Here is an example code snippet:

This will replace all instances of old_string with new_string in the file file.txt.

# Open the file in read mode
with open(‘file.txt’, ‘r’) as f:
# Read the contents of the file into a string
contents = f.read()

# Replace all instances of the target string
contents = contents.replace(‘old_string’, ‘new_string’)

# Open the file in write mode
with open(‘file.txt’, ‘w’) as f:
# Write the modified string to the file
f.write(contents)

# Close the file
f.close()

Shell script to replace all instances of a string in a file on Linux & Windows.

• On Linux via bash script

  sed “s/$stringToReplace/$replaceWith/g” $File_Name > $File_Name

• On Windows using Powershell

  ( get-content $File_Name ) | % { $_ -replace $stringToReplace, $replaceWith } | set-content $File_Name

• On Windows using Batch

  set str=teh cat in teh hat
  echo.%str%
  set str=%str:teh=the%
  echo.%str%

  Script Output:
  teh cat in teh hat
  the cat in the hat

• On Windows or Linux using Perl

  perl -pi.orig -e “s///g;”

• On Windows or Linux using Python

Source:

1. http://stackoverflow.com/questions/60034/how-can-you-find-and-replace-text-in-a-file-using-the-windows-command-line-envir