PING

Returns PONG if no argument is provided, otherwise return a copy of the argument as a bulk. This command is useful for:

1. Testing whether a connection is still alive.
2. Verifying the server's ability to serve data - an error is returned when this isn't the case (e.g., during load from persistence or accessing a stale replica).
3. Measuring latency.

If the client is in RESP2 and is subscribed to a channel or a pattern, it will instead return a multi-bulk with a "pong" in the first position and an empty bulk in the second position, unless an argument is provided in which case it returns a copy of the argument.

Examples

127.0.0.1:6379> PING
PONG
127.0.0.1:6379> 
127.0.0.1:6379> PING "hello world"
"hello world"