===== replace =====

Store a key/value pair, but only if it already exists.

**syntax:**
<code>
replace <key> <flags> <TTL> <length> [noreply] 
<value>
</code>

**parameters:**
  * **key** - The name of the unique key by which data is accessed.
  * **flags** - A 32-bit unsigned integer that the server stores with the data provided by the user, and returns along with the data when the item is retrieved.
  * **TTL** - The length of time (in seconds) the key/value pair will be stored in cache. A 0 value means the data will “never expire” and should not be removed from the cache unless required. If the TTL is more than 30 days then LSMCD interprets it as UNIX timestamp for expiration.
  * **length** - The length of the data in bytes that needs to be stored in LSMCD.
  * **noreply** - This **optional** parameter tells the server not to send any reply.
  * **value** - The data that needs to be stored. This parameter needs to be given on the new line after executing the command with the above options.

**example:** 
<code>
replace mykey 0 120 10
myvalueabc

STORED
</code>
**output notes:**
  * **0** → no flags
  * **120** → store data for 2 minutes (120 seconds)
  * **10** → data is 10 bytes long
  * **myvalueabc** → "mykey" will be associated with the value "myvalueabc"

**possible errors:**
  * **NOT_STORED** - Indicates that the provided key does not already exist in the LSMCD server so the data associated with that key could not be updated.