Grubbing Around

Nothing earth-shattering here: I recently had the “pleasure” of setting up an ARM64 server. After considerable support, several firmware upgrades, corruption of the main HDD, reinstallation of CentOS7 (recommended, somewhat to my surprise), all that remained was to get an up-to-date Linux built and installed with 32 bit binary support. This took a bit of make config fiddling, but got there after a few tries.

And then I had to relearn how grub/grub2 works in this brave new (to me) UEFI CentOS7 world. Herewith some brief commands I found useful while doing so…

sudo grep "^menu entry" /boot/efi/EFI/centos/grub.cfg \
     | tr -s " " | cut -f 2 -d "'" | cat -n

Edit /etc/default/grub to set GRUB_DEFAULT=N for desired value of N

Temporarily set the default for the next reboot:

sudo grub2-reboot 1 # based on output of above

Regenerate the grub2 configuration:

sudo grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg