Getblockhash

getblockhash height

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

Arguments:
1. height    (numeric, required) The height index

Result:
"hash"         (string) The block hash

Examples:
> bitcoin-cli getblockhash 1000
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getblockhash", "params": [1000] }' -H 'content-type: text/plain;' http://127.0.0.1:8332/