127.0.0.1:6379> expire name 2 #2秒失效 (integer) 1 127.0.0.1:6379> get name (nil) 127.0.0.1:6379> set name zhangfei OK 127.0.0.1:6379> ttl name #永久有效 (integer) -1 127.0.0.1:6379> expire name 30 #30秒失效 (integer) 1 127.0.0.1:6379> ttl name #还有24秒失效 (integer) 24 127.0.0.1:6379> ttl name #失效 (integer) -2