GNU GRUB
the GNU GRUB logo
Developer:	GNU Project
Latest release:	1.95 / October 15, 2006
Use:	Bootloader
License:	GNU General Public License
Website:	http://www.gnu.org/software/grub/

GNU GRUB ("GRUB" for short) is a boot loader package from the GNU Project. GRUB is the reference implementation of the Multiboot Specification, which allows a user to have several different operating systems on their computer at once, and to choose which one to run when the computer starts. GRUB can be used to select from different kernel images available on a particular operating system's partitions, as well as to pass boot-time parameters to such kernels. Image File history File links Grub2. ... Software development is the translation of a user need or marketing goal into a software product. ... The GNU logo, drawn by Etienne Suvasa The GNU Project was announced in 1983 by Richard Stallman. ... A software release refers to the creation and availability of a new version of a computer software product. ... October 15 is the 288th day of the year (289th in leap years). ... For the Manfred Mann album, see 2006 (album). ... In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ... A software license is a legal agreement which may take the form of a proprietary or gratuitous license as well as a memorandum of contract between a producer and a user of computer software. ... The GNU logo The GNU General Public License (GNU GPL or simply GPL) is a widely-used free software license, originally written by Richard Stallman for the GNU project. ... A Web site (or colloquially, Website) is a collection of Web pages, images, videos and other digital assets that is hosted on a Web server, usually accessible via the Internet or a LAN. A Web page is a document, typically written in HTML, that is almost always accessible via HTTP... In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ... The GNU logo, drawn by Etienne Suvasa The GNU Project was announced in 1983 by Richard Stallman. ... In computing, a reference implementation (or, infrequently, sample implementation) is a software example of a standard for use in helping others implement their own versions of the standard. ... Multiboot Specification is standard developed by Free Software Foundation which describes method of loading various kernels. ... An operating system (OS) is a set of computer programs that manage the hardware and software resources of a computer. ... A kernel connects the application software to the hardware of a computer. ...

GNU GRUB developed from a previous package called the GRand Unified Bootloader (a play on grand unified theory). GRUB can run on any operating system with a Multiboot kernel. It is predominantly used on Unix-like systems; the GNU operating system uses GNU GRUB as its boot loader, as do most general-purpose Linux distributions. Solaris has been able to boot using GRUB since version 10 1/06. Grand unification, grand unified theory, or GUT is a theory in physics that unifies the strong interaction and electroweak interaction. ... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... GNU is a free software operating system. ... It has been suggested that Linux be merged into this article or section. ... Solaris is a computer operating system developed by Sun Microsystems. ...

Features

GRUB loading Debian GNU/Linux.

GRUB is dynamically configurable; it loads its configuration at startup, allowing boot-time changes such as selecting different kernels or Initial RAM disks. To this end, GRUB provides a simple, bash-like command line interface, which lets users write new boot sequences. Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 113 KB, MIME type: image/jpeg) GRUB bootloader on Debian GNU/Linux. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution (1024 × 768 pixel, file size: 113 KB, MIME type: image/jpeg) GRUB bootloader on Debian GNU/Linux. ... Debian is a project based around the development of a free, complete operating system through the collaboration of volunteers from around the world. ... The initial ramdisk, or initrd is a temporary file system used by the Linux kernel during boot. ... This article is about the Unix shell. ... This article or section does not adequately cite its references or sources. ...

GRUB is highly portable. It supports multiple executable formats, and is geometry translation independent; while Multiboot compliant, it supports non-multiboot operating systems such as Microsoft Windows and OS/2 via a chain loading function. GRUB supports all commonly-used Unix file systems as well as VFAT and NTFS as used by Windows, and supports Logical Block Address (LBA) mode. GRUB allows users to view the contents of files on any supported file systems. Microsoft Windows is the name of several families of proprietary software operating systems by Microsoft. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Chain loading is a method used by computer programs to replace the currently executing program with a new program, using a common data area (a so-called core common area) to pass information from the current program to the new program. ... File Allocation Table (FAT) is a partially patented file system developed by Microsoft for MS-DOS and was the primary file system for consumer versions of Microsoft Windows up to and including Windows Me. ... NTFS, also known as NT File System or New Technology File System,[2] is the standard file system of Windows NT and its descendants Windows 2000, Windows XP, Windows Server 2003, and Windows Vista. ... Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disks. ...

GRUB can be used with a variety of different user interfaces. Most Linux distributions take advantage of GRUB's support for a graphical interface to provide a customized boot menu with a background image, and occasionally mouse support. GRUB's text interface can be set to use a serial link to provide a remote terminal boot loader access. The user interface is the part of a system exposed to users. ... A male DE-9 connector used for a serial port on a PC style computer. ...

GRUB can download operating system images from a network, and can thus support diskless systems. GRUB supports automatic decompression of OS images prior to booting from them.

GRUB boot process

When a computer is turned on, the computer's BIOS finds the primary bootable device (usually the computer's hard disk) and transfers control to the master boot record (MBR), the first 512 bytes of the hard disk. This article or section does not adequately cite its references or sources. ... A Master Boot Record (MBR), or partition sector, is the 512-byte boot sector that is the first sector (Sector 0) of a partitioned data storage device such as a hard disk. ...

The MBR contains GRUB stage 1. Given the small size of the MBR, Stage 1 does little more than load the next stage of GRUB (which may reside physically elsewhere on the disk). Stage 1 can either load Stage 2 directly, or it can load stage 1.5: GRUB Stage 1.5 is located in the first 30 kilobytes of hard disk immediately following the MBR. Stage 1.5 loads Stage 2.

When GRUB Stage 2 receives control, it presents an interface to the user in order to select which operating system to boot. This normally takes the form of a graphical menu, although if this is not available or the user wishes further control, GRUB has its own command prompt, where the user can manually specify the boot parameters. GRUB can also be set to automatically load a particular kernel after a timeout period.

Once boot options have been selected, GRUB loads the selected kernel into memory and passes control on to the kernel. At this stage GRUB can pass control of the boot process to another loader using chain loading if required by the operating system.

Installation

Unlike LILO, there is no need to reinstall GRUB to the MBR or a partition after a change to the configuration file. LILO (LInux LOader) is a boot loader for Linux developed by John Coffman. ...

In Linux, the "grub-install" command is used to install stage1 to either the MBR or a partition. GRUB's configuration file, stage2 (usually), and other files must be in a usable partition. If these files or the partition become unavailable stage1 will drop the user to the command line interface. This article or section does not adequately cite its references or sources. ...

The name and disk location of the GRUB configuration file varies from system to system; for example, in Debian GNU/Linux and openSUSE the file is stored in /boot/grub/menu.lst while Fedora Core uses /boot/grub/grub.conf. Fedora also provides a symbolic link from /etc/grub.conf to /boot/grub/grub.conf for compatibility reasons. Debian, created by the Debian Project, is a widely used distribution of free software developed through the collaboration of volunteers from around the world. ... Screenshot of SUSE Linux 10. ... Fedora Core is an RPM-based Linux distribution, developed by the community-supported Fedora Project and sponsored by Red Hat. ...

Instead of being installed on the system's hard disk, GRUB can be installed on removable media such as an optical drive (bios access, and el-torito) floppy disk or USB flash drive in order to bring up a system which cannot boot from its own disk. Removable media are transportable drives or disks that can be moved easily from one computer to another. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... A USB flash drive, shown with a 24 mm U.S. quarter coin for scale. ...

Development

The most used version of GRUB is referred to as "GRUB Legacy". This version is still receiving bug fixes but no new features are being added. The GRUB developers have switched their focus to GRUB 2, a complete rewrite whose most important goal is to make GNU GRUB cleaner, safer, more robust, more portable and more powerful. GRUB 2 started under the name PUPA. PUPA was supported by the Information-Technology Promotion Agency in Japan. PUPA was integrated into GRUB 2 development around 2002, when the GRUB version 0.9x was renamed GRUB Legacy. When GRUB 2 is released it will bear the name GNU GRUB. As of November 2006, GRUB 2 is still in development and not ready for production usage.

Some of the goals of the project included support for non-x86 platforms, international localization, non-ASCII characters, dynamic modules, memory management, a scripting mini-language, migrating platform specific (x86) code to platform specific modules, and an object-oriented framework. In computing, a platform describes some sort of framework, either in hardware or software, which allows software to run. ... Localization can mean any of the following: Generally, localization is the determination of the locality (position) of an object. ... Memory management is the act of managing computer memory. ...

References

• Brady, Pádraig. Details of GRUB on the PC. pixelbeat.org. Retrieved on 2006-11-22.

For the Manfred Mann album, see 2006 (album). ... November 22 is the 326th day (327th on leap years) of the year in the Gregorian calendar. ...

See also

• NTLDR
• LILO
• SILO
• elilo
• bootman

An NTLDR boot menu. ... LILO (LInux LOader) is a boot loader for Linux developed by John Coffman. ... The SPARC Improved bootLOader (SILO) is the bootloader used by the SPARC port of the Linux operating system; it can also be used for the Solaris operating system as a replacement for the standard Solaris boot loader. ... elilo is the standard Linux boot loader for EFI-based PC hardware. ... bootman is the BeOS boot loader. ...

External links

Free software Portal

• GNU GRUB Website
• Official GNU GRUB manual
• GRUB development wiki
• Freshmeat project page
• GRUB 2 Home Page
• Super Grub Disk Cdrom or floppy used for restoring grub to the mbr and much more.
• GRUB for DOS