[CentOS] Re-enable grub boot in UEFI (Windows took over it)

[Kay Diederichs]

On 02/05/2018 09:10 PM, Chris Murphy wrote:
> On Mon, Feb 5, 2018 at 8:27 AM, Kay Diederichs
> <kay.diederichs at uni-konstanz.de> wrote:
> 
>> grub-install /dev/nvme0n1
> 
> 
> Running this on computers with UEFI firmware is not good advice, it's
> an obsolete command. People should use the prebaked grubx64.efi binary
> that comes in the grub2-efi package, and is a signed binary so it can
> support UEFI Secure Boot.
> 
> If you run grub2-install, a new unsigned grub binary is created,
> replacing grubx64.efi. If you have Secure Boot enabled, you will not
> be able to boot, until you either reinstall the grub2-efi package (or
> you self-sign the grub2-install created binary and then go through the
> process of informing the firmware this is a valid binary by using
> mokutil - but I estimate maybe 1 in 50 people might do this).
> 
> 
> 
> 

Did you read my sentence "I recovered my Ubuntu grub menu ..." and that
this mentions grub-install, not grub2-install ? The procedure that I
describe is correct for Ubuntu - see e.g.
https://askubuntu.com/questions/831216/reinstalling-grub2-efi-partition
https://help.ubuntu.com/community/Grub2/Installing#Boot_repair_after_a_Windows_Upgrade_on_Ubuntu_14.04_.28non-RAID.29

The important point of my posting was to tell the OP the reason and
mechanism which leads to a loss of the grub menu. The OP already
described how s/he got the machine to boot again.