1 usb ubuntu bad
lsblk
update-grub
grub-install /dev/sdb
2 grub
ls (hd0,gpt0)/
ls (hd0,gpt2)/boot
root=(hd0,gpt2)
linux /boot/vmlinuz-5.15.0-122-generic root=/dev/sda2 ro
initrd /boot/initrd.img-5.15.0-122-generic
1 usb ubuntu bad
lsblk
update-grub
grub-install /dev/sdb
2 grub
ls (hd0,gpt0)/
ls (hd0,gpt2)/boot
root=(hd0,gpt2)
linux /boot/vmlinuz-5.15.0-122-generic root=/dev/sda2 ro
initrd /boot/initrd.img-5.15.0-122-generic