Replace domains in specified order in the given file.

url_replace.py

# python 3 imports
from __future__ import print_function

# imports
import fileinput
import re

# vars
domains_order = [
    'www.domain1.com',
    'www.domain2.com',
    'www.domain3.com',
]

domains = {
    'www.domain1.com',: 'replace.domain1.com',
    'www.domain2.com',: 'www.replaceddomain2.com',
    'www.domain3.com',: 'replace.domain3.com',
}


for line in fileinput.input(backup='.bak', inplace=True):
    for key in domains_order:
        # if key in domains:
        line = re.sub(key, domains[key], line.rstrip())
    print(line)