What is GRUB in Linux

GRUB (GNU GRand Unified Bootloader) is an operating system loader program in Linux. It provides the user with the option to choose the operating system or Linux kernel when booting the computer. GRUB works at earlier stages of booting, even before the operating system itself is launched.

Learn more about grub

GRUB provides the user with an interactive menu where you can select the desired operating system or Linux kernel to boot. It can detect other installed operating systems on the computer and add them to the boot menu. It also allows the user to change operating system boot parameters, such as passing kernel parameters, booting in safe mode, or changing the graphical screen resolution.

A special feature of GRUB is its configuration file, where boot settings are specified, including Linux kernels, boot parameters and additional settings. The GRUB configuration file is usually located in the /boot/grub directory. GRUB actually acts as a standard loader for most Linux distributions and plays an important role in successfully booting the operating system on the computer.

Features of grub in linux

GRUB (GNU GRand Unified Bootloader) in Linux has several features:

1. Configuration flexibility: Allows the user to configure the boot process, select operating systems or Linux kernels to boot, change boot parameters and manage various system parameters.
2. Multilingual support: Supports various languages and allows you to display an interactive download menu in the desired language, which is convenient for users from all over the world.
3. Detect and add Operating systems: Automatically detects the installed operating systems on the computer and adds them to the boot menu. This makes it easier to choose the right system at each boot.
4. Support for various file systems: Able to work with various file systems, such as ext4, NTFS, Btrfs and others. This allows you to load operating systems stored on different partitions and file systems.
5. Password Protection support: Allows you to set a password to access the interactive boot menu or protect boot settings from unauthorized changes.
6. Advanced Debugging features: Provides additional tools for debugging and diagnosing boot problems, such as a single-line command interface mode and the ability to change boot parameters manually.

GRUB is one of the most popular boot loaders in Linux and is widely used in various distributions, due to its flexibility and reliability.

What is grub recovery?

GRUB recovery in Linux means restoring the bootloader after it is damaged or deleted. GRUB recovery involves restoring one or more files necessary for its operation, such as configuration files, modules, and the bootloader itself. This allows the system to boot correctly again, providing access to the installed operating systems.

When is recovery needed?

GRUB recovery can be performed using various tools and methods, depending on the Linux distribution and the version of GRUB. For example, the grub-install command is often used to reinstall GRUB to disk, as well as the update-grub or grub-mkconfig commands to update or compile configuration files.

It may be necessary to restore the bootloader in the following cases:

1. After installing another operating system that overwritten GRUB. For example, if you installed Windows after Linux, then GRUB may be overwritten and need to be restored.
2. If you accidentally delete or damage configuration files or bootloader files, you may need to restore them.
3. If your system does not boot due to an error in GRUB or at earlier stages of booting, you can try to restore GRUB to fix the problem.
4. If you move partitions on your hard drive or resize them, GRUB may lose links to bootable images. In this case, GRUB recovery will help to restore the correct links.
5. In case you transfer your system to another hard drive or perform other disk manipulation.

Recovery provides the ability to boot the operating system from various hard disk partitions and monitors the loading of various operating systems installed on the computer.

When performing recovery, it is necessary to take into account the partitions and disk layout, installed operating systems and their boot images in order to determine exactly which files and parameters need to be restored. Recovery allows you to return the computer to normal operation.