backpack.sk

options:
    p: skript.backpack      # Permission needed for the command
    pm: &cNo permission!    # Permission message
    guiName: &8Backpack     # GUI name
    rows: 3                 # Backpack rows (Storage)

command /backpack [<text>]:
    permission: skript.backpack
    permission message: {@pm}
    trigger:
        open chest with {@rows} rows named "{@guiName}" to player
        wait 1 tick
        set {_num} to 0
        loop {backpack::%uuid of player%::*}:
            set slot {_num} of player's current inventory to loop-value
            add 1 to {_num}

on inventory close:
    if inventory name of player's current inventory contains "{@guiName}":
        loop 54 times:
            set {backpack::%uuid of player%::%loop-number - 1%} to slot "%loop-number - 1%" parsed as an integer of current inventory of player