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LPUSHX

Inserts a value at the head of the list stored at key, only if the list already exists. If the key does not exist, no operation is performed. When the key holds a value that is not a list, an error is returned.

Syntax​

LPUSHX key value

Details​

  • Available since: 2.0.0
  • Time complexity: O(1)
  • ACL categories: @write, @list, @fast

Example​

Assume we have an empty list called mylist. Now, let's try to add element "a" to mylist:

LPUSHX mylist "a"

Since mylist does not exist initially, no operation is performed.

RESP2/RESP3 Reply​

Integer reply: the length of the list after the push operation, or 0 if no operation was performed.