Calculate the git blob hash of

git-hash-of-files.py

#!/usr/bin/python3
"""Hashes the contents of files matching git.

Example of how to get the get hash allowing `git cat-file -p <hash>` to work.
The output of the files should match `git ls-tree HEAD -r -t`.
"""
from sys import argv
from hashlib import sha1


if __name__ == '__main__':
    for filename in argv[1:]:
        with open(filename, 'rb') as f:
            h = sha1()
            data = f.read()
            h.update(f"blob {len(data)}\0".encode('utf-8'))
            h.update(data)
            print(h.hexdigest())

I guess at some point git will change to sha256...

Note that the \r\n issues can occur here. Either sync with settings in git or adapt with

with open(filename, 'r') as f:
    h = sha1()
    data = f.read().replace("\r", "").encode("utf-8")
    h.update(f"blob {len(data)}\0".encode('utf-8'))
    h.update(data)
    print(h.hexdigest())