getblockhash height

The getblockhash RPC returns the header hash of a block at the given height in the local best block chain.

bitcoin-cli getblockhash ...
Note: The height of the block whose header hash should be returned. The height of the hardcoded genesis block is 0.

*bitcoin-cli help getblockhash

getblockhash height

Returns hash of block in best-block-chain at height provided.

1. height         (numeric, required) The height index

"hash"         (string) The block hash

> bitcoin-cli getblockhash 1000
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getblockhash", "params": [1000] }' -H 'content-type: text/plain;'