Search notes:

/boot/grub/grub.cfg

grub.cfg is the configuration file for GRUB (usually located under /boot/grub).

This configuration file is written in a language that is similar a shell variant (for example bash), particularly, it has variables, conditionals and loops.

grub.cfg is usually created by grub-mkconfig using templates files under /etc/grub.d and settings from /etc/default/grub.

initrd: Apparently, init ram disks are created with cpio.

set default=0
set timeout=5

insmod ext2

set root=(hd0,msdos2)

menuentry "GNU/Linux, Linux tq84" {

  linux /boot/bzImage root=/dev/sda2
  initrd /boot/microcode.img

}

/boot/grub/grub.cfg

See also