Python IO用哈希码替换/覆盖文本文件

Question

I need to overwrite each line of a (txt) file in python with (first 10 digits of) it's hashcode.

I'm having troubles with the writing part ( I can print it but not write it). the old part of the file('x) should be overwritten with the new part(the hash).

[FAIL] File passwords.txt should be transformed from ['x'] to ['2d711642b7']

Expected value: ['2d711642b7'] Actual value: ['x', '2d711642b7']

def hash_file(filename):

    import hashlib
    import fileinput
    from hashlib import sha256

    with open(filename,'rb+') as f:

        for line in f:
            hash =sha256(line.rstrip()).hexdigest()
            b = bytes(hash[0:10], 'utf-8')
            f.write(b)

Answer 1

You can use fileinput and open the file in inplace mode.

from __future__ import print_function
from hashlib import sha256
import fileinput

def hash_file(filename):
    for line in fileinput.input(filename, inplace=True):
        line_bytes = line.rstrip().encode('utf-8')
        hash_10 = sha256(line_bytes).hexdigest()[:10]
        print(hash_10, end='\n')
        # for python 2, print hash_10,

Example input:

x
y
z

becomes:

2d711642b7
a1fce43638
594e519ae4

PS : As it turns out, inplace is not actually inplace. Under the hood, a copy of the original file is created.