find_duplicates.py
"""This module contains a code example related to
Think Python, 2nd Edition
by Allen Downey
http://thinkpython2.com
Copyright 2015 Allen Downey
License: http://creativecommons.org/licenses/by/4.0/
"""
from __future__ import print_function, division
import os
def walk(dirname):
"""Finds the names of all files in dirname and its subdirectories.
dirname: string name of directory
"""
names = []
if '__pycache__' in dirname:
return names
for name in os.listdir(dirname):
path = os.path.join(dirname, name)
if os.path.isfile(path):
names.append(path)
else:
names.extend(walk(path))
return names
def compute_checksum(filename):
"""Computes the MD5 checksum of the contents of a file.
filename: string
"""
cmd = 'md5sum ' + filename
return pipe(cmd)
def check_diff(name1, name2):
"""Computes the difference between the contents of two files.
name1, name2: string filenames
"""
cmd = 'diff %s %s' % (name1, name2)
return pipe(cmd)
def pipe(cmd):
"""Runs a command in a subprocess.
cmd: string Unix command
Returns (res, stat), the output of the subprocess and the exit status.
"""
# Note: os.popen is deprecated
# now, which means we are supposed to stop using it and start using
# the subprocess module. But for simple cases, I find
# subprocess more complicated than necessary. So I am going
# to keep using os.popen until they take it away.
fp = os.popen(cmd)
res = fp.read()
stat = fp.close()
assert stat is None
return res, stat
def compute_checksums(dirname, suffix):
"""Computes checksums for all files with the given suffix.
dirname: string name of directory to search
suffix: string suffix to match
Returns: map from checksum to list of files with that checksum
"""
names = walk(dirname)
d = {}
for name in names:
if name.endswith(suffix):
res, stat = compute_checksum(name)
checksum, _ = res.split()
if checksum in d:
d[checksum].append(name)
else:
d[checksum] = [name]
return d
def check_pairs(names):
"""Checks whether any in a list of files differs from the others.
names: list of string filenames
"""
for name1 in names:
for name2 in names:
if name1 < name2:
res, stat = check_diff(name1, name2)
if res:
return False
return True
def print_duplicates(d):
"""Checks for duplicate files.
Reports any files with the same checksum and checks whether they
are, in fact, identical.
d: map from checksum to list of files with that checksum
"""
for key, names in d.items():
if len(names) > 1:
print('The following files have the same checksum:')
for name in names:
print(name)
if check_pairs(names):
print('And they are identical.')
if __name__ == '__main__':
d = compute_checksums(dirname='.', suffix='.py')
print_duplicates(d)