Handling File and Directory Paths

There are two main modules in Python that deals with path manipulation. One is the os.path module and the other is the pathlib module. The pathlib module was added in Python 3.4, offering an object-oriented way to handle file system paths.

Backslash on Windows and Forward Slash on OS X and Linux

On Windows, paths are written using backslashes (\) as the separator between folder names. On Unix based operating system such as macOS, Linux, and BSDs, the forward slash (/) is used as the path separator. Joining paths can be a headache if your code needs to work on different platforms.

Fortunately, Python provides easy ways to handle this. We will showcase how to deal with this with both os.path.join and pathlib.Path.joinpath

Using os.path.join on Windows:

import os

os.path.join('usr', 'bin', 'spam')

And using pathlib on *nix:

from pathlib import Path

print(Path('usr').joinpath('bin').joinpath('spam'))

pathlib also provides a shortcut to joinpath using the / operator:

from pathlib import Path

print(Path('usr') / 'bin' / 'spam')

Notice the path separator is different between Windows and Unix based operating system, that’s why you want to use one of the above methods instead of adding strings together to join paths together.

Joining paths is helpful if you need to create different file paths under the same directory.

Using os.path.join on Windows:

my_files = ['accounts.txt', 'details.csv', 'invite.docx']

for filename in my_files:
    print(os.path.join('C:\\Users\\asweigart', filename))

Using pathlib on *nix:

my_files = ['accounts.txt', 'details.csv', 'invite.docx']
home = Path.home()
for filename in my_files:
    print(home / filename)

The Current Working Directory

Using os on Windows:

import os

os.getcwd()

os.chdir('C:\\Windows\\System32')
os.getcwd()

Using pathlib on *nix:

from pathlib import Path
from os import chdir

print(Path.cwd())

chdir('/usr/lib/python3.6')
print(Path.cwd())

Creating New Folders

Using os on Windows:

import os

os.makedirs('C:\\delicious\\walnut\\waffles')

Using pathlib on *nix:

from pathlib import Path
cwd = Path.cwd()
(cwd / 'delicious' / 'walnut' / 'waffles').mkdir()

Oh no, we got a nasty error! The reason is that the ‘delicious’ directory does not exist, so we cannot make the ‘walnut’ and the ‘waffles’ directories under it. To fix this, do:

from pathlib import Path
cwd = Path.cwd()
(cwd / 'delicious' / 'walnut' / 'waffles').mkdir(parents=True)

And all is good :)

Absolute vs. Relative Paths

There are two ways to specify a file path.

  • An absolute path, which always begins with the root folder
  • A relative path, which is relative to the program’s current working directory

There are also the dot (.) and dot-dot (…) folders. These are not real folders but special names that can be used in a path. A single period (“dot”) for a folder name is shorthand for “this directory.” Two periods (“dot-dot”) means “the parent folder.”

Handling Absolute and Relative Paths

To see if a path is an absolute path:

Using os.path on *nix:

import os

os.path.isabs('/')

os.path.isabs('..')

Using pathlib on *nix:

from pathlib import Path
Path('/').is_absolute()

Path('..').is_absolute()

You can extract an absolute path with both os.path and pathlib

Using os.path on *nix:

import os

os.getcwd()

os.path.abspath('..')

Using pathlib on *nix:

from pathlib import Path

print(Path.cwd())

print(Path('..').resolve())

You can get a relative path from a starting path to another path.

Using os.path on *nix:

import os

os.path.relpath('/etc/passwd', '/')

Using pathlib on *nix:

from pathlib import Path

print(Path('/etc/passwd').relative_to('/'))

Checking Path Validity

Checking if a file/directory exists:

Using os.path on *nix:

import os
os.path.exists('.')

os.path.exists('setup.py')

os.path.exists('/etc')

os.path.exists('nonexistentfile')

Using pathlib on *nix:

from pathlib import Path
Path('.').exists()

Path('setup.py').exists()

Path('/etc').exists()

Path('nonexistentfile').exists()

Checking if a path is a file:

Using os.path on *nix:

import os
os.path.isfile('setup.py')

os.path.isfile('/home')

os.path.isfile('nonexistentfile')

Using pathlib on *nix:

from pathlib import Path

Path('setup.py').is_file()

Path('/home').is_file()

Path('nonexistentfile').is_file()

Checking if a path is a directory:

Using os.path on *nix:

import os
os.path.isdir('/')

os.path.isdir('setup.py')

os.path.isdir('/spam')

Using pathlib on *nix:

from pathlib import Path

Path('/').is_dir()

Path('setup.py').is_dir()

Path('/spam').is_dir()

Finding File Sizes and Folder Contents

Getting a file’s size in bytes:

Using os.path on Windows:

import os
os.path.getsize('C:\\Windows\\System32\\calc.exe')

Using pathlib on *nix:

from pathlib import Path

stat = Path('/bin/python3.6').stat()
print(stat) # stat contains some other information about the file as well

print(stat.st_size) # size in bytes

Listing directory contents using os.listdir on Windows:

import os
os.listdir('C:\\Windows\\System32')

Listing directory contents using pathlib on *nix:

from pathlib import Path

for f in Path('/usr/bin').iterdir():
    print(f)

To find the total size of all the files in this directory:

WARNING: Directories themselves also have a size! So you might want to check for whether a path is a file or directory using the methods in the methods discussed in the above section!

Using os.path.getsize() and os.listdir() together on Windows:

import os

total_size = 0

for filename in os.listdir('C:\\Windows\\System32'):
      total_size = total_size + os.path.getsize(os.path.join('C:\\Windows\\System32', filename))

print(total_size)

Using pathlib on *nix:

from pathlib import Path
total_size = 0

for sub_path in Path('/usr/bin').iterdir():
    total_size += sub_path.stat().st_size

print(total_size)

Copying Files and Folders

The shutil module provides functions for copying files, as well as entire folders.

import shutil, os

os.chdir('C:\\')

shutil.copy('C:\\spam.txt', 'C:\\delicious')

shutil.copy('eggs.txt', 'C:\\delicious\\eggs2.txt')
   'C:\\delicious\\eggs2.txt'

While shutil.copy() will copy a single file, shutil.copytree() will copy an entire folder and every folder and file contained in it:

import shutil, os

os.chdir('C:\\')
shutil.copytree('C:\\bacon', 'C:\\bacon_backup')

Moving and Renaming Files and Folders

import shutil

shutil.move('C:\\bacon.txt', 'C:\\eggs')

The destination path can also specify a filename. In the following example, the source file is moved and renamed:

shutil.move('C:\\bacon.txt', 'C:\\eggs\\new_bacon.txt')

If there is no eggs folder, then move() will rename bacon.txt to a file named eggs.

shutil.move('C:\\bacon.txt', 'C:\\eggs')

Permanently Deleting Files and Folders

  • Calling os.unlink(path) or Path.unlink() will delete the file at path.

  • Calling os.rmdir(path) or Path.rmdir() will delete the folder at path. This folder must be empty of any files or folders.

  • Calling shutil.rmtree(path) will remove the folder at path, and all files and folders it contains will also be deleted.

Safe Deletes with the send2trash Module

You can install this module by running pip install send2trash from a Terminal window.

import send2trash

with open('bacon.txt', 'a') as bacon_file: # creates the file
    bacon_file.write('Bacon is not a vegetable.')

send2trash.send2trash('bacon.txt')

Walking a Directory Tree

import os

for folder_name, subfolders, filenames in os.walk('C:\\delicious'):
    print('The current folder is {}'.format(folder_name))

    for subfolder in subfolders:
        print('SUBFOLDER OF {}: {}'.format(folder_name, subfolder))
    for filename in filenames:
        print('FILE INSIDE {}: {}'.format(folder_name, filename))

    print('')

pathlib provides a lot more functionality than the ones listed above, like getting file name, getting file extension, reading/writing a file without manually opening it, etc. Check out the official documentation if you want to know more!

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