Reorganize a directory into subfolders the same way git organizes its object files.

hashtree.py

#!/usr/bin/env python3

"""
Reduce the size of a directory by creating new directories for each
unique combination of the first two letters of the existing files.
This is the same way that git stores object files.

For example, a file with this name would result in the following:

fff394e6-214d-4f74-8607-d6825f17c8fd
  |
  V
ff/f394e6-214d-4f74-8607-d6825f17c8fd

This has the potential to reduce the root directory size by a factor of 256 (assuming file names are in hex).
"""

import os
import sys
import shutil
from os.path import join

directories = set()

parent = sys.argv[1]
for fname in os.listdir(parent):
    prefix = fname[:2]
    newname = fname[2:]
    newdir = join(parent, prefix)
    if prefix not in directories:
        os.makedirs(newdir, exist_ok=True)
        directories.add(prefix)
        print(f'created directory {prefix}')
    shutil.move(join(parent, fname), join(newdir, newname))