stlabels 

List labels that have receiving addresses
> bitcoin-cli listlabels receive

List labels that have sending addresses
> bitcoin-cli listlabels send

As a JSON-RPC call
> curl --user myusername --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "listlabels", "params": [receive]}' -H 'content-type: text/plain;' http://127.0.0.1:8332/


