Print the coinbase data for all ancestors of a block, up to a specified block height

print_coinbase.py

import json
import subprocess

tip = "00000000000000002b3ca56c3fdef9a74b8758bc7da5d9c9aecd79ed922a3692"
FORK_HEIGHT = 679555


def print_chain(tip_hash: str, min_height: int = FORK_HEIGHT):
    """Print block information starting at a given chain tip and going
    backward up to (and including) the block with height min_height"""
    block = json.loads(subprocess.check_output(
        ['bitcoin-cli', 'getblock', tip_hash]))
    height = block["height"]
    if height < min_height:
        return
    coinbase_id = block["tx"][0]
    print(f"Block height {height}; hash {tip_hash}; coinbase tx {coinbase_id}")
    tx = json.loads(subprocess.check_output(
        ['bitcoin-cli', 'getrawtransaction', coinbase_id, "true", tip_hash]))
    coinbase_data = bytes.fromhex(tx["vin"][0]["coinbase"])
    print(coinbase_data)
    assert b"ZULUPooL-" in coinbase_data

    parent_hash = block["previousblockhash"]
    print_chain(parent_hash, min_height)


if __name__ == '__main__':
    print_chain(tip, FORK_HEIGHT)