212 – Patterns in glob search

The method glob of pathlib.Path can look for file names that match patterns using character ranges. The syntax for a character range is the same as in regular expressions, and it’s the square brackets [...] with two characters separated by a hyphen. For example, the character range [0-9] matches any of the ten digits in the string "0123456789".

Suppose your current working directory has these files:

- 01_ideas.txt
- 02_todo.txt
- 03_cover.png
- draft.txt

The first three files have a numeric prefix but only two of them are text files (.txt). If you wanted to find all text files with a numeric prefix, you could use two character ranges to do that:

import pathlib

for txt_file in pathlib.Path().glob("[0-9][0-9]*.txt"):
    print(txt_file.name)
# 01_ideas.txt
# 02_todo.txt

The character ranges [0-9][0-9] match the initial numeric prefix and the asterisk * matches an arbitrary file name. The final .txt matches the literal characters ".txt".

Note that the patterns that glob supports may look like those of regular expressions, but they are not the same thing. glob supports a much more limited set of patterns.