Password Censor

pass.py

#!/usr/bin/env python
import sys

""" Takes any file with format:
        <hash>:<password>
    as an argument. Example:
    `python pass.py list.txt`
    Include a second argument for output. Example:
    `python pass.py list.txt output.txt`
    Alternatively, you can use stdout:
    `python pass.py list.txt > newList.txt`

    Author: John Pacific (Tux)
"""

# Read the file and grab contents and seperate the input by delimited colons
# and delete the newline char (\n)
with open(sys.argv[1]) as file:
    contents = [line.rstrip().split(':') for line in file]

# Censor out everything but the first and last chars.
newContents = []
for item in contents:
    password = item[1]
    password = password.replace(password[1:-1], '*'*len(password[1:-1]))
    newContents.append("{}:{}\n".format(item[0], password))

# If you included a second argument for output:
if len(sys.argv) > 2:
    with open(sys.argv[2], 'w+') as file:
        for line in newContents:
            file.write(line)
else:
    for line in newContents:
        sys.stdout.write(line)

Input (as file):

8846f7eaee8fb117ad06bdd830b7586c:password
57d583aa46d571502aad4bb7aea09c70:user
938df8b296dd15d0dce8eaa37be593e0:backup
a25b2710ba9de114396adc7dfb0a7235:Admin

Output (as stdout or in file):

8846f7eaee8fb117ad06bdd830b7586c:p******d
57d583aa46d571502aad4bb7aea09c70:u**r
938df8b296dd15d0dce8eaa37be593e0:b****p
a25b2710ba9de114396adc7dfb0a7235:A****n