HD (hierarchical deterministic) wallets contain master private key, from which all the private keys can be derived.
Is there a CLI tool that calculates the private keys out of a HD key?
You can use
ku utility provided in pycoin library.
ku -s 0/0-2 xprv9xWkBDfyBXmZsA85GyWj9uYPyoQv826YAadKWMaaEosNrFBKgj2TqWuiWY3zuqxYGpHfv9cnGj5P7e8EskpzKL1Y8Gk9aX6QbryA5raK73p
will generate keys from index 0-2 on derivation path 0/x