# LMOVE ```json metadata { "schema_version": 2, "title": "LMOVE", "description": "Returns an element after popping it from one list and pushing it to another. Deletes the list if the last element was moved.", "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"], "arguments": [{"display_text":"source","key_spec_index":0,"name":"source","type":"key"},{"display_text":"destination","key_spec_index":1,"name":"destination","type":"key"},{"arguments":[{"display_text":"left","name":"left","token":"LEFT","type":"pure-token"},{"display_text":"right","name":"right","token":"RIGHT","type":"pure-token"}],"name":"wherefrom","type":"oneof"},{"arguments":[{"display_text":"left","name":"left","token":"LEFT","type":"pure-token"},{"display_text":"right","name":"right","token":"RIGHT","type":"pure-token"}],"name":"whereto","type":"oneof"}], "syntax_fmt": "LMOVE source destination \u003cLEFT | RIGHT\u003e \u003cLEFT | RIGHT\u003e", "complexity": "O(1)", "group": "list", "command_flags": ["write","denyoom"], "acl_categories": ["@write","@list","@slow"], "since": "6.2.0", "arity": 5, "key_specs": [{"RW":true,"access":true,"begin_search":{"spec":{"index":1},"type":"index"},"delete":true,"find_keys":{"spec":{"keystep":1,"lastkey":0,"limit":0},"type":"range"}},{"RW":true,"begin_search":{"spec":{"index":2},"type":"index"},"find_keys":{"spec":{"keystep":1,"lastkey":0,"limit":0},"type":"range"},"insert":true}], "tableOfContents": {"sections":[{"id":"required-arguments","title":"Required arguments"},{"id":"examples","title":"Examples"},{"children":[{"id":"pattern-reliable-queue","title":"Pattern: reliable queue"},{"id":"pattern-circular-list","title":"Pattern: circular list"}],"id":"details","title":"Details"},{"id":"redis-software-and-redis-cloud-compatibility","title":"Redis Software and Redis Cloud compatibility"},{"id":"return-information","title":"Return information"}]} , "codeExamples": [] } ``` > [!NOTE] > This command's behavior varies in clustered Redis environments. See the [multi-key operations](https://redis.io/docs/latest/develop/using-commands/multi-key-operations) page for more information. Atomically returns and removes the first/last element (head/tail depending on the `wherefrom` argument) of the list stored at `source`, and pushes the element at the first/last element (head/tail depending on the `whereto` argument) of the list stored at `destination`. For example: consider `source` holding the list `a,b,c`, and `destination` holding the list `x,y,z`. Executing `LMOVE source destination RIGHT LEFT` results in `source` holding `a,b` and `destination` holding `c,x,y,z`. If `source` does not exist, the value `nil` is returned and no operation is performed. If `source` and `destination` are the same, the operation is equivalent to removing the first/last element from the list and pushing it as first/last element of the list, so it can be considered as a list rotation command (or a no-op if `wherefrom` is the same as `whereto`). This command comes in place of the now deprecated [`RPOPLPUSH`](https://redis.io/docs/latest/commands/rpoplpush). Doing `LMOVE RIGHT LEFT` is equivalent. ## Required arguments
source The key of the source list.
destination The key of the destination list.
LEFT | RIGHT The end of `source` to pop the element from: `LEFT` (head) or `RIGHT` (tail).
LEFT | RIGHT The end of `destination` to push the element to: `LEFT` (head) or `RIGHT` (tail).
## Examples redis> RPUSH mylist "one" (integer) 1 redis> RPUSH mylist "two" (integer) 2 redis> RPUSH mylist "three" (integer) 3 redis> LMOVE mylist myotherlist RIGHT LEFT "three" redis> LMOVE mylist myotherlist LEFT RIGHT "one" redis> LRANGE mylist 0 -1 1) "two" redis> LRANGE myotherlist 0 -1 1) "three" 2) "one" ## Details ### Pattern: reliable queue Redis is often used as a messaging server to implement processing of background jobs or other kinds of messaging tasks. A simple form of queue is often obtained pushing values into a list in the producer side, and waiting for this values in the consumer side using [`RPOP`](https://redis.io/docs/latest/commands/rpop) (using polling), or [`BRPOP`](https://redis.io/docs/latest/commands/brpop) if the client is better served by a blocking operation. However in this context the obtained queue is not _reliable_ as messages can be lost, for example in the case there is a network problem or if the consumer crashes just after the message is received but it is still to process. `LMOVE` (or [`BLMOVE`](https://redis.io/docs/latest/commands/blmove) for the blocking variant) offers a way to avoid this problem: the consumer fetches the message and at the same time pushes it into a _processing_ list. It will use the [`LREM`](https://redis.io/docs/latest/commands/lrem) command in order to remove the message from the _processing_ list once the message has been processed. An additional client may monitor the _processing_ list for items that remain there for too much time, and will push those timed out items into the queue again if needed. ### Pattern: circular list Using `LMOVE` with the same source and destination key, a client can visit all the elements of an N-elements list, one after the other, in O(N) without transferring the full list from the server to the client using a single [`LRANGE`](https://redis.io/docs/latest/commands/lrange) operation. The above pattern works even in the following conditions: * There are multiple clients rotating the list: they'll fetch different elements, until all the elements of the list are visited, and the process restarts. * Even if other clients are actively pushing new items at the end of the list. The above makes it very simple to implement a system where a set of items must be processed by N workers continuously as fast as possible. An example is a monitoring system that must check that a set of web sites are reachable, with the smallest delay possible, using a number of parallel workers. Note that this implementation of workers is trivially scalable and reliable, because even if a message is lost the item is still in the queue and will be processed at the next iteration. ## Redis Software and Redis Cloud compatibility | Redis
Software | Redis
Cloud | Notes | |:----------------------|:-----------------|:------| | ✅ Standard
✅ Active-Active | ✅ Standard
✅ Active-Active | | ## Return information **RESP2:** [Bulk string reply](../../develop/reference/protocol-spec#bulk-strings): the element being popped and pushed. **RESP3:** [Bulk string reply](../../develop/reference/protocol-spec#bulk-strings): the element being popped and pushed.