Boot0000* ubuntu    HD(1,GPT,4d8fdbeb-d6f8-4cce-86f9-f9dff8695276,0x28,0x64000)/File(EFIubuntushimx64.efi)
Boot0080* Mac OS X  PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)/Sata(0,0,0)/HD(2,GPT,cf2dd05b-2789-4d07-83c7-018ae532d035,0x64028,0xe19bfb0)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,c005e716a459d9459d1475bbdc249c88)/File(C78C0B9E-B1FA-38E2-8591-C135881B3B4ASystemLibraryCoreServicesboot.efi)
Boot0081* Recovery OS   PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)/Sata(0,0,0)/HD(2,GPT,cf2dd05b-2789-4d07-83c7-018ae532d035,0x64028,0xa60d400)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,1be0b02a55ba594f91a1f6008c00aa5c)/File(C78C0B9E-B1FA-38E2-8591-C135881B3B4Aboot.efi)
Boot0082*   PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)/Sata(0,0,0)/HD(2,GPT,cf2dd05b-2789-4d07-83c7-018ae532d035,0x64028,0xa60d400)/VenMedia(be74fcf7-0b7c-49f3-9147-01f4042e6842,c005e716a459d9459d1475bbdc249c88)/File(C78C0B9E-B1FA-38E2-8591-C135881B3B4ASystemLibraryCoreServicesboot.efi)
BootFFFF*   PciRoot(0x0)/Pci(0x1c,0x5)/Pci(0x0,0x0)/Sata(0,0,0)/HD(3,GPT,d8d6f046-d9e2-4b48-a5ae-0e225f7926b3,0x7dbffd8,0x4000000)/File(SystemLibraryCoreServicesboot.efi)

sudo blkid | grep -i fat
/dev/sdb2: UUID="2641-087E" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="27141f73-5de4-4785-8894-3c774fae7e79"

sudo mkdir /mnt/efi
sudo mount /dev/sdb2 /mnt/efi

sudo find /mnt/efi/ -type f -iname '*.efi'

sudo update-grub

sudo mkdir /mnt/efi/boot
sudo cp -r /boot/grub /mnt/efi/boot/grub

search.fs_uuid 77b2d888-07e2-4d80-be84-ef1a584a194c root hd0,gpt6
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg