Find a file in python

Question

I have a file that may be in a different place on each user's machine. Is there a way to implement a search for the file? A way that I can pass the file's name and the directory tree to search in?

Answer 1

os.walk is the answer, this will find the first match:

import os

def find(name, path):
    for root, dirs, files in os.walk(path):
        if name in files:
            return os.path.join(root, name)

And this will find all matches:

def find_all(name, path):
    result = []
    for root, dirs, files in os.walk(path):
        if name in files:
            result.append(os.path.join(root, name))
    return result

And this will match a pattern:

import os, fnmatch
def find(pattern, path):
    result = []
    for root, dirs, files in os.walk(path):
        for name in files:
            if fnmatch.fnmatch(name, pattern):
                result.append(os.path.join(root, name))
    return result

find('*.txt', '/path/to/dir')

Answer 2

In Python 3.4 or newer you can use pathlib to do recursive globbing:

>>> import pathlib
>>> sorted(pathlib.Path('.').glob('**/*.py'))
[PosixPath('build/lib/pathlib.py'),
 PosixPath('docs/conf.py'),
 PosixPath('pathlib.py'),
 PosixPath('setup.py'),
 PosixPath('test_pathlib.py')]

Reference: https://docs.python.org/3/library/pathlib.html#pathlib.Path.glob

In Python 3.5 or newer you can also do recursive globbing like this:

>>> import glob
>>> glob.glob('**/*.txt', recursive=True)
['2.txt', 'sub/3.txt']

Reference: https://docs.python.org/3/library/glob.html#glob.glob

Answer 3

I used a version of os.walk and on a larger directory got times around 3.5 sec. I tried two random solutions with no great improvement, then just did:

paths = [line[2:] for line in subprocess.check_output("find . -iname '*.txt'", shell=True).splitlines()]

While it's POSIX-only, I got 0.25 sec.

From this, I believe it's entirely possible to optimise whole searching a lot in a platform-independent way, but this is where I stopped the research.

Answer 4

If you are using Python on Ubuntu and you only want it to work on Ubuntu a substantially faster way is the use the terminal's locate program like this.

import subprocess

def find_files(file_name):
    command = ['locate', file_name]

    output = subprocess.Popen(command, stdout=subprocess.PIPE).communicate()[0]
    output = output.decode()

    search_results = output.split('\n')

    return search_results

search_results is a list of the absolute file paths. This is 10,000's of times faster than the methods above and for one search I've done it was ~72,000 times faster.

Answer 5

If you are working with Python 2 you have a problem with infinite recursion on windows caused by self-referring symlinks.

This script will avoid following those. Note that this is windows-specific!

import os
from scandir import scandir
import ctypes

def is_sym_link(path):
    # http://stackoverflow.com/a/35915819
    FILE_ATTRIBUTE_REPARSE_POINT = 0x0400
    return os.path.isdir(path) and (ctypes.windll.kernel32.GetFileAttributesW(unicode(path)) & FILE_ATTRIBUTE_REPARSE_POINT)

def find(base, filenames):
    hits = []

    def find_in_dir_subdir(direc):
        content = scandir(direc)
        for entry in content:
            if entry.name in filenames:
                hits.append(os.path.join(direc, entry.name))

            elif entry.is_dir() and not is_sym_link(os.path.join(direc, entry.name)):
                try:
                    find_in_dir_subdir(os.path.join(direc, entry.name))
                except UnicodeDecodeError:
                    print "Could not resolve " + os.path.join(direc, entry.name)
                    continue

    if not os.path.exists(base):
        return
    else:
        find_in_dir_subdir(base)

    return hits

It returns a list with all paths that point to files in the filenames list. Usage:

find("C:\\", ["file1.abc", "file2.abc", "file3.abc", "file4.abc", "file5.abc"])

Answer 6

Below we use a boolean "first" argument to switch between first match and all matches (a default which is equivalent to "find . -name file"):

import  os

def find(root, file, first=False):
    for d, subD, f in os.walk(root):
        if file in f:
            print("{0} : {1}".format(file, d))
            if first == True:
                break 

Answer 7

The answer is very similar to existing ones, but slightly optimized.

So you can find any files or folders by pattern:

def iter_all(pattern, path):
    return (
        os.path.join(root, entry)
        for root, dirs, files in os.walk(path)
        for entry in dirs + files
        if pattern.match(entry)
    )

either by substring:

def iter_all(substring, path):
    return (
        os.path.join(root, entry)
        for root, dirs, files in os.walk(path)
        for entry in dirs + files
        if substring in entry
    )

or using a predicate:

def iter_all(predicate, path):
    return (
        os.path.join(root, entry)
        for root, dirs, files in os.walk(path)
        for entry in dirs + files
        if predicate(entry)
    )

to search only files or only folders - replace “dirs + files”, for example, with only “dirs” or only “files”, depending on what you need.

Regards.

Answer 8

SARose's answer worked for me until I updated from Ubuntu 20.04 LTS. The slight change I made to his code makes it work on the latest Ubuntu release.

import subprocess

def find_files(file_name):
    command = ['locate'+ ' ' + file_name]
    output = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True).communicate()[0]
    output = output.decode()
    search_results = output.split('\n')
    return search_results

Answer 9

@F.M.F's answers has a few problems in this version, so I made a few adjustments to make it work.

import os
from os import scandir
import ctypes

def is_sym_link(path):
    # http://stackoverflow.com/a/35915819
    FILE_ATTRIBUTE_REPARSE_POINT = 0x0400
    return os.path.isdir(path) and (ctypes.windll.kernel32.GetFileAttributesW(str(path)) & FILE_ATTRIBUTE_REPARSE_POINT)

def find(base, filenames):
    hits = []

    def find_in_dir_subdir(direc):
        content = scandir(direc)
        for entry in content:
            if entry.name in filenames:
                hits.append(os.path.join(direc, entry.name))

            elif entry.is_dir() and not is_sym_link(os.path.join(direc, entry.name)):
                try:
                    find_in_dir_subdir(os.path.join(direc, entry.name))
                except UnicodeDecodeError:
                    print("Could not resolve " + os.path.join(direc, entry.name))
                    continue
                except PermissionError:
                    print("Skipped " + os.path.join(direc, entry.name) + ". I lacked permission to navigate")
                    continue

    if not os.path.exists(base):
        return
    else:
        find_in_dir_subdir(base)

    return hits

unicode() was changed to str() in Python 3, so I made that adjustment (line 8)

I also added (in line 25) and exception to PermissionError. This way, the program won't stop if it finds a folder it can't access.

Finally, I would like to give a little warning. When running the program, even if you are looking for a single file/directory, make sure you pass it as a list. Otherwise, you will get a lot of answers that not necessarily match your search.

example of use:

find("C:\", ["Python", "Homework"])

or

find("C:\\", ["Homework"])

but, for example: find("C:\\", "Homework") will give un-wanted answers.

I would be lying if I said I know why this happens. Again, this is not my code and I just made the adjustments I needed to make it work. All credit should go to @F.M.F.