What is the difference between os.path.basename() and os.path.dirname()?

Both functions use the os.path.split(path) function to split the pathname path into a pair; (head, tail).

The os.path.dirname(path) function returns the head of the path.

E.g.: The dirname of '/foo/bar/item' is '/foo/bar'.

The os.path.basename(path) function returns the tail of the path.

E.g.: The basename of '/foo/bar/item' returns 'item'

From: http://docs.python.org/3/library/os.path.html#os.path.basename

To summarize what was mentioned by Breno above

Say you have a variable with a path to a file

path = '/home/User/Desktop/myfile.py'

os.path.basename(path) returns the string 'myfile.py'

and

os.path.dirname(path) returns the string '/home/User/Desktop' (without a trailing slash '/')

These functions are used when you have to get the filename/directory name given a full path name.

In case the file path is just the file name (e.g. instead of path = '/home/User/Desktop/myfile.py' you just have myfile.py), os.path.dirname(path) returns an empty string.

Linux/macOS:

Windows:

Image sources: Linux/macOS; Windows.

Note that since Python 3.4, one can use pathlib.Path, as explained on https://miguendes.me:

Linux/macOS:

>>> from pathlib import Path

>>> path = Path('/home/miguel/projects/blog/config.tar.gz')

>>> path.drive
'/'

>>> path.root
'/'

>>> path.anchor
'/'

>>> path.parent
PosixPath('/home/miguel/projects/blog')

>>> path.name
'config.tar.gz'

>>> path.stem
'config.tar'

>>> path.suffix
'.gz'

>>> path.suffixes
['.tar', '.gz']

Windows:

>>> from pathlib import Path

>>> path = Path(r'C:/Users/Miguel/projects/blog/config.tar.gz')

>>> path.drive
'C:'

>>> path.root
'/'

>>> path.anchor
'C:/'

>>> path.parent
WindowsPath('C:/Users/Miguel/projects/blog')

>>> path.name
'config.tar.gz'

>>> path.stem
'config.tar'

>>> path.suffix
'.gz'

>>> path.suffixes
['.tar', '.gz']