Gamerules in Minecraft "Unknown Command" [duplicate]
From here:
/gamerule
Sets or queries a game rule value.
Syntax
Computer
gamerule <rule name> [value]
Pocket Edition
gamerule <rule: string> <value: bool>
gamerule <rule: string> <value: int>
gamerule [rule: string]
-
Additionally, issuing /gamerule by itself will list available game rules.
The particular gamerule you are seeking is called keepInventory.
Issue the following command:
/gamerule keepInventory true
You seem to use /gamerules instead of the correct one /gamerule. It is without the s on the end.