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Arch Linux

Arch Linux (or Arch) is an operating system intended to be lightweight and simple.^[1] The design approach of the development team focuses on "simplicity", elegance, code correctness and minimalism.^[2] "Simplicity", according to Arch, is defined as "...without unnecessary additions, modifications, or complications.." and is defined from a developer standpoint, rather than a user standpoint.^[3]

Inspired by CRUX, another minimalist distribution, Judd Vinet started Arch Linux in March 2002. Vinet led the project until 1 October 2007, when he stepped down due to lack of time, transferring control of the project to Aaron Griffin.^[4] The Arch in Arch Linux is pronounced [??rt?] or [a?t?] (as in archer or parchment).^[5]

Design and principles

init framework

Installation
Package management

Pacman
Repositories
ABS
AUR

Versions

"Rolling releases"
Release history

Live Arch environments
See also
References
External links

Design and principles

Arch is largely based around binary packages. Packages are targeted for i686 and x86-64 microprocessors to assist performance on modern hardware. A ports/ebuild-like system is also provided for automated source compilation, known as the ABS (Arch Build System).

The Arch focus on simplicity and economy for developers means, among other things, that the main effort in assisting the user is not expended in crafting GUI configuration tools - the package manager, for example, does not have an official graphical frontend - but making well-annotated configuration files and extensive use of shell scripts^[6]. This has earned it a reputation as a distribution for "intermediate and advanced Linux users who aren't afraid of the command line" ^[7].

init framework

Arch uses a BSD-style init framework, a tradeoff of flexibility for simplicity. It also includes and permits use of System V runlevels and the inittab file, but there is little differentiation between runlevels. This is due to the fact that the modules and daemons loaded at startup are arranged very simply as arrays in the central configuration file, /etc/rc.conf, as opposed to System V's system of a directory for each runlevel containing a numbered symbolic link for each daemon. There is also the ability to start processes asynchronously, which neither the original BSD init nor the original Sys V init have. See init for more detail on the differences between the two systems.

Installation

The Arch Linux website supplies both CD (ISO) and USB (IMG) images for ease of use. In keeping with the Arch commitment to the KISS principle, the Arch Linux installer is simply a shell script using dialog for user interaction (~ 10-15 minutes). The slim default install provides only a base GNU/Linux environment, including the GNU toolchain, the Linux kernel, a few extra modules and libraries, and the bash shell.^[8] Further system customization and expansion (adding additional software such as a window manager, desktop environment, etc.) must be done manually, installing packages downloaded from online repositories. Arch is therefore generally considered relatively involved to install, in comparison to other operating systems. ^[9]

Package management

Pacman

All packages are managed using the Pacman package manager, which handles package installation, upgrades, removal and downgrades, and features automatic dependency resolution. The packages for Arch Linux are obtained from the Arch Linux package tree and are optimized for either i686 or x86-64 architectures. Arch Linux is primarily based on binary packages in the tar.gz format for installation speed.

Repositories

Currently there are four official repositories:

core, which contains all the packages needed to set up a base system
extra, which holds packages not required for the base system, including desktop environments and programs
testing, a special repository, with packages that are candidates for the core or extra repositories.
community, which contains packages built and voted on by the community; includes packages that have sufficient votes and have been adopted by a "trusted user".

The Unstable repository was dropped in July 2008 and most of the packages moved to other repositories. ^[10]. In addition to the official repositories there are a number of unofficial user repositories (PUR).

ABS

ABS is a ports-like source packaging system which compiles source tarballs into binary packages, that are installed via Pacman.^[11] ABS provides a directory tree of shell scripts called PKGBUILDS, which enable any and all official Arch packages to be customized and compiled. Rebuilding the entire system using modified compiler flags is also supported by ABS. The ABS makepkg tool can be used to create custom .pkg.tar.gz packages from third-party sources. The resulting packages are also cleanly installable and trackable via pacman.

AUR

In addition to the repositories, the Arch Linux User-community Repository (AUR) provides user-made PKGBUILD scripts for packages not included in the repositories. The PKGBUILD scripts simplify building from source by explicitly listing and checking for dependencies and configuring the install to match the Arch architecture. The scripts are available for download on the archlinux.org web site but programs such as "yaourt" can further streamline the downloading and building process. A tool such as "Yaourt" that searches and downloads PKGBUILD scripts and runs them automatically will not be included in the official repositories.^[12]

The AUR provides the community with packages that are not included in the repositories. Reasons include:

License issues. Software that cannot be redistributed, but is free to use, can be included in the AUR since all that is hosted by the Arch Linux web site is a shell script that downloads the actual software from elsewhere. Examples include proprietary freeware such as Google Earth and RealPlayer.
Modified official packages. The AUR also contains many variations on the official packaging as well as beta versions of software that is contained within the repositories as stable releases.

PKGBUILDS for any software can be contributed by ordinary users and any PKGBUILD that is not confined to the AUR for policy reasons can be voted into the community repositories.

Versions

"Rolling releases"

Unlike major distributions such as Debian, Fedora, Ubuntu and others, Arch Linux does not schedule releases for specific dates but uses a "rolling release" system, with new packages provided daily. Its package management permits users to keep systems up-to-date easily.^[13] Rather than encouraging users to move between discrete releases, Arch Linux releases are simply snapshots of the current set of packages, sometimes with revised installation software. Therefore it makes no difference from which snapshot Arch gets installed if updates are installed afterwards. As of November 2008, the latest image is 2008.06 (Overlord), dated 24 June 2008.

Release history

Date	Version	Codename
2008-06-24	2008.06	Overlord
2007-08-05	2007.08	Don't Panic
2007-05-17	2007.05	Duke
2007-03-31	0.8	Voodoo
2005-01-24	0.7	Wombat
2004-03-01	0.6	Widget
2003-06-21	0.5	Nova
2002-12-18	0.4	Dragon
2002-08-07	0.3	Firefly
2002-04-17	0.2	Vega
2002-03-11	0.1	Homer

Live Arch environments

The official Arch install media presents the user with a basic Arch system replete with standard CLI tools from which the installer can be run. For the user who wishes to have access to a full GUI without or before installing, live CDs have been developed: