compare_dirs.py

#!/usr/bin/env python3

'''
A script to recursively compare two directories (including file size and file hash changes)
Usage: python3 compare_dirs.py DIR1 DIR2
'''

import os, sys, hashlib, unicodedata

COMPARE_FILES = True            # should file sizes be compared if their names are the same?
MD5 = True                      # should file hash sums be compared if their names and sizes are the same?
COLORIZE = False                # colorization for bash (only Linux & Unix)
BUFF_SIZE = 1<<26               # 64 MB buffer

def md5sum(fn):
    hasher = hashlib.md5()
    with open(fn, "rb") as f:
        chunk = f.read(BUFF_SIZE)
        while chunk:
            hasher.update(chunk)
            chunk = f.read(BUFF_SIZE)
    return hasher.hexdigest()

WHITE, RED, GREEN = 15, 196, 46
fg = lambda text, color: "\33[38;5;" + str(color) + "m" + text + "\33[0m"

# Some SSDs change bytecodes of Unicode names from NFC to NFD; need to normalize
NFD = lambda x: unicodedata.normalize('NFD', x)

def compare_dirs(d1: "old directory name", d2: "new directory name"):
    def print_local(a, msg):
        text = '{} {} {}'.format('DIR ' if a[2] else 'FILE', a[1], msg)
        if COLORIZE:
            color = {'added': GREEN, 'removed': RED}.get(msg, WHITE)
            print(fg(text, color))
        else:
            print(text)
    # Ensure validity
    for d in [d1,d2]:
        if not os.path.isdir(d):
            raise ValueError("not a directory: " + d)
    # Get relative path
    l1 = [(NFD(fn), os.path.join(d1, fn)) for fn in os.listdir(d1)]
    l2 = [(NFD(fn), os.path.join(d2, fn)) for fn in os.listdir(d2)]
    # Determine type: directory or file?
    l1 = sorted([(fn, pth, os.path.isdir(pth)) for fn, pth in l1])
    l2 = sorted([(fn, pth, os.path.isdir(pth)) for fn, pth in l2])
    i1 = i2 = 0
    cnt = 0
    common_dirs = []
    while i1<len(l1) and i2<len(l2):
        if l1[i1][0] == l2[i2][0]:      # same name
            if l1[i1][2] == l2[i2][2]:  # same type
                if l1[i1][2]:           
                    # Pair of directories -> remember the name for recursion
                    common_dirs.append((l1[i1][1], l2[i2][1]))
                elif COMPARE_FILES:
                    # Pair of files -> compare their sizes
                    size1 = os.stat(l1[i1][1]).st_size
                    size2 = os.stat(l2[i2][1]).st_size
                    if size1!=size2:
                        print_local(l1[i1],'size changed: {:d} -> {:d}'.format(size1, size2))
                    elif MD5:
                        # Sizes are the same -> compare MD5 hashes
                        if md5sum(l1[i1][1])!=md5sum(l2[i2][1]):
                            print_local(l1[i1],'hash changed')
            else:
                print_local(l1[i1],'type changed')
            i1 += 1
            i2 += 1
        elif l1[i1][0]<l2[i2][0]:
            print_local(l1[i1],'removed')
            i1 += 1
        elif l1[i1][0]>l2[i2][0]:
            print_local(l2[i2],'added')
            i2 += 1
        cnt += 1
    while i1<len(l1):
        print_local(l1[i1],'removed')
        i1 += 1
        cnt += 1
    while i2<len(l2):
        print_local(l2[i2],'added')
        i2 += 1
        cnt += 1
    # Compare subfolders recursively
    for sdir1,sdir2 in common_dirs:
        cnt += compare_dirs(sdir1, sdir2)
    return cnt

if __name__=='__main__':
    print ('Comparing files {}abled'.format('en' if COMPARE_FILES else 'dis'))
    print ('MD5 checking {}abled'.format('en' if MD5 else 'dis'))
    print ('Colorization {}abled'.format('en' if COLORIZE else 'dis'))
    print (compare_dirs(sys.argv[1], sys.argv[2]), 'items compared')

Nice script! Found it via the stackoverflow question.
The obvious addition would be to check the time last modified (even before the size?) and other metadata like creation time, permissions, etc.
Maybe I'll fork it and add those, if I have time.

Thanks.

The obvious addition would be to check the time last modified (even before the size?) and other metadata like creation time, permissions, etc.

The original purpose of this script was to ensure two directories have same structure. Later I added MD5 sum comparison to recursively ensure that two directories and their files are identical. Since I want to read and compare all files anyway, adding time comparison did not seem useful, since the script is already sufficiently fast in my view (though checking times could decrease number of MD5 comparisons).

But you are welcome to fork and/or modify as you see fit.