write and Replace particular line in file

Question

I want to replace value of key(i.e db_host, addons_path) with $$$$.

Input text file contains the following:

#         


        

Answer 1

use fileinput module.

import fileinput

for line in fileinput.input('data.txt',backup='.bak',inplace=1):
    print line.rstrip().replace('Python','Perl') 
    #or print line.replace('Python','Perl'),