fnmatch – Unix filename pattern matching in Python

This module is used for matching Unix shell-style wildcards. fnmatch() compares a single file name against a pattern and returns TRUE if they match else returns FALSE.
The comparison is case-sensitive when the operating system uses a case-sensitive file system.
The special characters and their functions used in shell-style wildcards are :

• ‘*’ – matches everything
• ‘?’ – matches any single character
• ‘[seq]’ – matches any character in seq
• ‘[!seq]’ – matches any character not in seq

The meta-characters should be wrapped in brackets for a literal match. For example, ‘[?]’ matches the character ‘?’.

Functions provided by the fnmatch module

1. fnmatch.fnmatch(filename, pattern): This function tests whether the given filename string matches the pattern string and returns a boolean value. If the operating system is case-insensitive, then both parameters will be normalized to all lower-case or upper-case before the comparison is performed.

   Example: Script to search all files starting with ‘fnmatch’ and ending in ‘.py’

   # Python program to illustrate
   # fnmatch.fnmatch(filename, pattern)
   import fnmatch
   import os
   
   pattern = 'fnmatch_*.py'
   print ('Pattern :', pattern )
   print()
   
   files = os.listdir('.')
   for name in files:
       print ('Filename: %-25s %s' % (name, fnmatch.fnmatch(name, pattern))

   Output :

   $ python fnmatch_fnmatch.py
   
   Pattern : fnmatch_*.py
   
   Filename: __init__.py               False
   Filename: fnmatch_filter.py         True
   Filename: fnmatch_fnmatch.py        True
   Filename: fnmatch_fnmatchcase.py    True
   Filename: fnmatch_translate.py      True
   Filename: index.rst                 False
   

2. fnmatch.fnmatchcase(filename, pattern): This function performs the case sensitive comparison and tests whether the given filename string matches the pattern string and returns a boolean value.

   Example: Script for a case-sensitive comparison, regardless of the filesystem and operating system settings.

   # Python program to illustrate
   # fnmatch.fnmatchcase(filename, pattern)
   import fnmatch
   import os
   
   pattern = 'FNMATCH_*.PY'
   print ('Pattern :', pattern)
   print()
   
   files = os.listdir('.')
   
   for name in files:
       (print 'Filename: %-25s %s' % (name, fnmatch.fnmatchcase(name, pattern)))

   Output :

   $ python fnmatch_fnmatchcase.py
   
   Pattern : FNMATCH_*.PY
   
   Filename: __init__.py               False
   Filename: fnmatch_filter.py         False
   Filename: FNMATCH_FNMATCH.PY        True
   Filename: fnmatch_fnmatchcase.py    False
   Filename: fnmatch_translate.py      False
   Filename: index.rst                 False
   

3. fnmatch.filter(names, pattern): This function returns the subset of the list of names passed in the function that match the given pattern.
   

   Example: Filter files by more than one file extension.

   # Python program to illustrate
   # fnmatch.filter(names, pattern)
   import fnmatch
   import os
   
   pattern = 'fnmatch_*.py'
   print ('Pattern :', pattern )
   
   files = os.listdir('.')
   print ('Files :', files)
   
   print ('Matches :', fnmatch.filter(files, pattern))

   Output :

   $ python fnmatch_filter.py
   
   Pattern : fnmatch_*.py
   Files   : ['__init__.py', 'fnmatch_filter.py', 'fnmatch_fnmatch.py', 
   'fnmatch_fnmatchcase.py', 'fnmatch_translate.py', 'index.rst']
   Matches : ['fnmatch_filter.py', 'fnmatch_fnmatch.py',
   'fnmatch_fnmatchcase.py', 'fnmatch_translate.py']
   

4. fnmatch.translate(pattern): This function returns the shell-style pattern converted to a regular expression for using with re.match() (re.match() will only match at the beginning of the string and not at the beginning of each line).

   # Python program to illustrate
   # fnmatch.translate(pattern)
   import fnmatch, re
   
   regex = fnmatch.translate('*.txt')
   reobj = re.compile(regex)
   
   print(regex)
   print(reobj.match('foobar.txt'))

   Output :

   '(?s:.*\\.txt)\\Z'
   _sre.SRE_Match object; span=(0, 10), match='foobar.txt'
   

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