Changing the selection of a partition without gparted

I freshly installed EOS in EFI mode and gave the EFI partition the boot/efi flag during installation. But after the installation there is only mfsdata behind it (looked again in live-system with gparted). now i can mark it with gparted as esp/boot afterwards. But I don’t want to install gparted again in the live-system, because I will never need it again when everything is ready. I want to keep my system as minimal as possible. So: how can I change such a partition marker WITHOUT gparted?

Is it working? If so, it is probably fine the way it is. It is possible gparted just doesn’t show it the way you expect.

If you want to make changes, one easy way is to boot the live ISO and use it to make changes to your installed partitions using gparted or kde partition manager.

Alternatively, you could use a terminal-based tool like parted, cgdisk, gdisk, etc.

Here is an example with parted:

sudo parted /dev/sda -- set 3 boot on

In this case, 3 is the partition number so it sets the boot flag on /dev/sda3