This command is very similar to DEL: it removes the specified keys.
Just like DEL a key is ignored if it does not exist. However the command
performs the actual memory reclaiming in a different thread, so it is not
blocking, while DEL is. This is where the command name comes from: the
command just unlinks the keys from the keyspace. The actual removal
will happen later asynchronously.
Examples
127.0.0.1:6379> SET key1 "Hello"
OK
127.0.0.1:6379> SET key2 "World"
OK
127.0.0.1:6379> UNLINK key1 key2 key3
(integer) 2