GRUBbased

GRUBbased is a term used to describe bootloaders that are built on the GNU Grand Unified Bootloader (GRUB). In practice it refers to GRUB 2, the modern implementation that superseded GRUB Legacy, and to any bootloader components that rely on the GRUB architecture. GRUBbased bootloaders act as the initial stage of the boot process, presenting a boot menu, loading a kernel image and an initial RAM filesystem, and passing kernel parameters chosen at boot time.

GRUBbased bootloaders are modular and portable across firmware interfaces. They can reside in the Master Boot Record, a partition boot sector, or in the EFI System Partition for UEFI systems. They operate in BIOS/CSM mode or in pure UEFI mode. The user-visible configuration is produced from a set of scripts and default settings, typically processed to generate the grub.cfg file found under /boot/grub. GRUB 2 uses a scripting language and a rich set of modules to support file systems, LVM, RAID, encryption, and network boot, as well as chainloading other bootloaders.

Common features include multi-boot support (booting Linux, Windows, and other OSes), kernel parameter handling, initramfs loading, and compatibility with modern storage and partitioning schemes (GPT, MBR, LUKS, LVM, btrfs). UEFI Secure Boot can be supported with signed bootloaders.

GRUBbased bootloaders are standard in most major Linux distributions, including Debian/Ubuntu, Fedora, openSUSE, and Arch. They replaced older bootloaders such as LILO in many systems, while remaining capable of interfacing with alternative bootloaders through chainloading.