what is linux grub
In Linux, grub is a complete program used to load and manage system startup. It is a boot program; it is the first software that runs when the computer starts, and loads the kernel of the operating system. It is up to the kernel to initialize other parts of the operating system. grub supports LBA, which puts the addressing translation used to find files into the hard drive's firmware.
The operating environment of this tutorial: Ubuntu 16.04 system, Dell G3 computer.
GRUB in Linux
GRUB is a complete program for loading and managing system startup. It is the most common bootloader in Linux distributions. The bootloader is very important because without it the operating system cannot be started.
The boot program is the first software that runs when the computer starts. The boot loader transfers control to the operating system kernel.
It loads the kernel of the operating system, and then the kernel initializes other parts of the operating system (including Shell, display manager, desktop environment, etc.).
GRUB is the default bootloader for many Linux distributions. This is because it is better than many previous versions of bootloaders. Some of its features are:
GRUB supports LBA (Logical Block Addressing Mode), which puts the addressing translation used to find files into the hard drive’s firmware
GRUB provides maximum flexibility to load the required options for the operating system using a command-based pre-operating system environment.
Boot options such as kernel parameters can be modified using the GRUB command line.
There is no need to specify the physical location of the Linux kernel for GRUB. It only requires the kernel's hard drive number, partition number and file name.
GRUB can start almost all operating systems using direct loading and chain loading startup methods.
Boot Program and Boot Manager
I don’t want to confuse you right now, but I think this topic It is inevitable. There is a blurry line between the boot loader and the boot manager.
You already know what a bootloader is. It starts first, then loads the kernel into memory and executes it. The boot manager allows you to choose between different operating systems (if you have more than one operating system on your computer). The boot manager does not load the system directly.
With the introduction of Linux kernel version 3.3, the Linux kernel includes a built-in EFI bootloader. In fact, any EFI-enabled system includes an EFI bootloader. In systems that support EFI, the firmware reads the EFI files in the EFI System Partition (ESP) to obtain boot information.
Insert a picture here, which shows the partition table with the ESP partition:
GRUB is both a boot program and a boot manager . I'll talk about GRUB in a moment. Let's first look at other GRUB-like programs.
Little knowledge: GRUB is the abbreviation of GRand Unified Bootloader.
GRUB What do those lines on the screen mean?
You will see a few lines on the GRUB screen. These lines will be different for different setups and different distributions.
Normally, the first line is your Linux distribution. If you see something like advanced options, you can go into it and find some lines that start with "linux-generic-x-y-z" etc.
When your Linux distribution updates a kernel version, it will keep at least one older version. You can choose to boot into an older Linux kernel in case your system encounters any issues with the newly updated Linux kernel.
In Ubuntu-based distributions, you may also see a recovery option.
At the end, you may see an entry such as System Settings or UEFI Settings to access your system's BIOS settings.
What other boot managers are similar to GRUB?
GRUB is the most popular boot manager in Linux. But it's not the only one. There is a highly customizable boot manager called rEFInd Boot Manager, which is also loved by some Linux users.
There is also a text-based boot manager called systemd-boot. As you can guess this is intended for systemd based Linux distributions. There are some distributions that are using systemd-boot, such as Pop OS.
Accessing or editing GRUB
Normally the GRUB screen you see is its menu interface. If you have more than one operating system installed, it will allow you to choose one to start. If your Linux distribution has more than one kernel installed, you can also choose to load a different kernel.
Depending on the configuration of different Linux distributions, there may be some other options on your GRUB menu.
You can press the e key in the GRUB menu interface to edit menu items. This way you can modify the parameters of the kernel before it is loaded. For example, in some cases, disabling the graphics driver provided by the kernel can help you solve the problem of Linux system getting stuck at startup.
You can also press the c key on the GRUB menu interface to enter the GRUB command line menu.
GRUB Configuration File
Any changes you make to GRUB in the menu interface are temporary. If you want to make some permanent changes to GRUB, such as changing the default timeout, you can modify the GRUB configuration file after the Linux system starts.
The default GRUB configuration file is /etc/default/grub. There is also a /etc/default/grub.d directory, which also stores some configurations. You can edit the /etc/default/grub file directly, but I recommend making additional modifications by adding configuration files (.cfg files) in this directory.
You must update GRUB for these changes to take effect.
Use the GRUB Customizer to customize GRUB
If you are not used to using a text editor to edit files in the terminal, you can use a A graphical tool called GRUB Customizer.
It allows you to change the startup sequence, default timeout, etc. You can also use it to set the GRUB background to a custom wallpaper.
The GRUB customizer can be installed from the Universe repository in Ubuntu 20.04 and via a PPA in Ubuntu 18.04. It is available in Arch Linux-based distributions via the AUR.
Related recommendations: "Linux Video Tutorial"
The above is the detailed content of what is linux grub. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

DeepSeek is a powerful intelligent search and analysis tool that provides two access methods: web version and official website. The web version is convenient and efficient, and can be used without installation; the official website provides comprehensive product information, download resources and support services. Whether individuals or corporate users, they can easily obtain and analyze massive data through DeepSeek to improve work efficiency, assist decision-making and promote innovation.

There are many ways to install DeepSeek, including: compile from source (for experienced developers) using precompiled packages (for Windows users) using Docker containers (for most convenient, no need to worry about compatibility) No matter which method you choose, Please read the official documents carefully and prepare them fully to avoid unnecessary trouble.

BITGet is a cryptocurrency exchange that provides a variety of trading services including spot trading, contract trading and derivatives. Founded in 2018, the exchange is headquartered in Singapore and is committed to providing users with a safe and reliable trading platform. BITGet offers a variety of trading pairs, including BTC/USDT, ETH/USDT and XRP/USDT. Additionally, the exchange has a reputation for security and liquidity and offers a variety of features such as premium order types, leveraged trading and 24/7 customer support.

Ouyi OKX, the world's leading digital asset exchange, has now launched an official installation package to provide a safe and convenient trading experience. The OKX installation package of Ouyi does not need to be accessed through a browser. It can directly install independent applications on the device, creating a stable and efficient trading platform for users. The installation process is simple and easy to understand. Users only need to download the latest version of the installation package and follow the prompts to complete the installation step by step.

Gate.io is a popular cryptocurrency exchange that users can use by downloading its installation package and installing it on their devices. The steps to obtain the installation package are as follows: Visit the official website of Gate.io, click "Download", select the corresponding operating system (Windows, Mac or Linux), and download the installation package to your computer. It is recommended to temporarily disable antivirus software or firewall during installation to ensure smooth installation. After completion, the user needs to create a Gate.io account to start using it.

Ouyi, also known as OKX, is a world-leading cryptocurrency trading platform. The article provides a download portal for Ouyi's official installation package, which facilitates users to install Ouyi client on different devices. This installation package supports Windows, Mac, Android and iOS systems. Users can choose the corresponding version to download according to their device type. After the installation is completed, users can register or log in to the Ouyi account, start trading cryptocurrencies and enjoy other services provided by the platform.

Gate.io is a highly acclaimed cryptocurrency trading platform known for its extensive token selection, low transaction fees and a user-friendly interface. With its advanced security features and excellent customer service, Gate.io provides traders with a reliable and convenient cryptocurrency trading environment. If you want to join Gate.io, please click the link provided to download the official registration installation package to start your cryptocurrency trading journey.

This tutorial guides you through installing and configuring Nginx and phpMyAdmin on an Ubuntu system, potentially alongside an existing Apache server. We'll cover setting up Nginx, resolving potential port conflicts with Apache, installing MariaDB (
