I want to append text after certain word in a file with python.

Let's take an example :-

• Say I have a config.py
• Contains of file are as follows:

# Configuration file for my python program
username = '' # plain text username
password = '' # hashed version

• After my programs runs, it takes inputs for username and password
• Then the program converts password to some hash (say md5)
• Now I want to add that username and hashed password in the config file
• config.py should look like this :

 # Configuration file for my python program
 username = 'example_username' # plain text username
 password = 'sdtbrw6vw456546vb' # hashed version

I don't know to do that, can someone please help to solve me this?

CodePudding user response：

This should work as you want:

import re

username = 'the username'
password = 'the hash'

with open('config.py', 'r') as file:
    text = re.sub(r"username = '.*?'", f"username = '{username}'", file.read())
    text = re.sub(r"password = '.*?'", f"password = '{password}'", text)


with open('config.py', 'w') as file:
    file.write(text)

But, If you want to do this to save stuff, using JSON is a lot better and easier.

CodePudding user response：

Since you are working with configuration files. There is a configparser module in python that is used for this.

For example:

Define your config.ini as:

[APP]
environment = test
debug = true

[DATABASE]
username = test_user
password = test_pass
host = 127.0.0.1s
port = 5432
db = test_db

Then you can manipulate configuration as:

from configparser import SafeConfigParser

if __name__ == "__main__":
    config = SafeConfigParser()
    config.read("config.ini")

    print(config["DATABASE"]["USERNAME"])  # Prints: test_user

    config.set("DATABASE", "USERNAME", "test")  # Updates USERNAME to "test"

    with open("config.ini", "w") as configfile:  # Save config
        config.write(configfile)

Also check this article to find more options: From Novice to Expert: How to Write a Configuration file in Python