Module 6: Blocks and Blockchain State

Reading Block Data

After mining blocks in regtest or syncing a mainnet/testnet node, you can inspect block data using several bitcoin-cli commands.

Get the hash of the most recent block:

Retrieve full block data using the hash:

To get just the header:

This includes:

Get block hash by height:

Example:

Using getchaintips and Understanding Chain Re-orgs

The command getchaintips returns all known tips of the blockchain:

This is useful in regtest when you're simulating chain reorganizations. For example, if you invalidate a block:

Then generate a longer competing chain (replace <miner_address> with your mining address):

Your node will adopt the longer chain tip, causing a re-org. This is how Bitcoin resolves consensus forks.

Understanding Confirmations and Depth

A transaction's confirmation count is equal to the number of blocks on top of the block that includes it.

To see how many confirmations a transaction has (replace <txid> with an actual transaction ID):

You’ll see:

Alternatively, use :

To simulate confirmations in regtest, simply mine more blocks (replace <miner_address> with your mining address):

This simulates time passing and increases confirmation depth instantly.

Inspecting Mempool Transactions

The mempool holds transactions waiting to be mined. In regtest, it’s typically empty unless you send a transaction before mining.

List all mempool transactions:

Get details of a specific mempool transaction (replace <txid> with an actual transaction ID):

This shows:

You can clear the mempool by restarting the node or by mining a block that confirms the pending transactions.