PING

PING [message]

Available since:

1.0.0

Time complexity:

O(1)

ACL categories:

@fast, @connection,

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 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.

Return

Simple string reply, and specifically PONG, when no argument is provided.

Bulk string reply the argument provided, when applicable.

Examples