How do I change the UEFI Boot Order from within Windows 10?

Question

I have multiple Operating systems installed, each with their respective EFI file in the ESP (EFI System Partition).

For example: I have Windows 10 at \EFI\Boot\Microsoft\bootmgr.efi, and I have WinPE at \EFI\WinPE\Boot\bootx64.efi

When I boot into my BIOS I can see the list of operating systems, but I would like to be able to give windows a command to change the order and then shutdown, effectively telling Windows to boot into a different operating system.

Solution

This is not documented anywhere by Microsoft. However I was able to look through the source code of Grub2Win to see how they accomplished switching order.

Aparrently there is a bcdedit object called {fwbootmgr} if you change the display order of that item, it will effectively change the Boot order within the UEFI.

bcdedit /set {fwbootmgr} displayorder <ID_OF_NEW_OS> {bootmgr}

You can get the id of the other UEFI entries by doing: bcdedit /enum {fwbootmgr} and looking at the boot entries under displayorder.