Available since: 1.0.0
Time complexity: O(1)
Returns the remaining time to live of a key that has a timeout. This introspection capability allows a Redis client to check how many seconds a given key will continue to be part of the dataset.
In Redis 2.6 or older the command returns
-1 if the key does not exist or if the key exist but has no associated expire.
Starting with Redis 2.8 the return value in case of error changed:
-2if the key does not exist.
-1if the key exists but has no associated expire.
See also the
PTTL command that returns the same information with milliseconds resolution (Only available in Redis 2.6 or greater).
Integer reply: TTL in seconds, or a negative value in order to signal an error (see the description above).