uptime
Returns the total uptime of the server.
Result:
n (numeric) The number of seconds that the server has been running
Examples:
> bitcoin-cli uptime
> curl --user myusername --data-binary '{"jsonrpc": "2.0", "id": "curltest", "method": "uptime", "params": []}' -H 'content-type: application/json' http://127.0.0.1:8332/