Available since: 2.6.0
Time complexity: O(1)
TTL this command returns the remaining time to live of a key that has an
expire set, with the sole difference that
TTL returns the amount of remaining
time in seconds while
PTTL returns it in milliseconds.
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.
Integer reply: TTL in milliseconds, or a negative value in order to signal an error (see the description above).