GRUB2 & the Boot Process
GRUB2
GRUB2 is the standard bootloader. It loads the kernel and initramfs and passes kernel parameters.
| File / command | Purpose |
|---|---|
/etc/default/grub | Main GRUB config (edit this) |
/boot/grub2/grub.cfg | Generated config - do not edit by hand |
grub2-mkconfig -o /boot/grub2/grub.cfg | Regenerate config (RHEL) |
update-grub | Regenerate config (Debian) |
Kernel parameters are set via GRUB_CMDLINE_LINUX. Temporary edits can be made at boot by pressing e.
Exam tip: To reset a lost root password you boot to an emergency shell by appendingrd.break(RHEL) orinit=/bin/bashat the GRUB prompt.