When Redis is configured to use an ACL file (with the aclfile configuration
option), this command will save the currently defined ACLs from the server memory to the ACL file.
*Return value
Simple string reply: OK on success.
The command may fail with an error for several reasons: if the file cannot be written or if the server is not configured to use an external ACL file.
*Examples
> ACL SAVE
+OK
> ACL SAVE
-ERR There was an error trying to save the ACLs. Please check the server logs for more information