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A Linux distribution, often simply '''distribution''' or '''distro''', is a member of the Linux family of Unix-like Operating System s comprising the Linux Kernel , the non-kernel parts of the GNU Operating System , and assorted other software. Because most (if not all) of the kernel and software packages are Free And Open Source , Linux distributions have taken a wide variety of forms —from fully-featured desktop and server operating systems to minimal environments (typically for use in embedded systems, or for booting from a floppy). Aside from certain custom software (such as installers and configuration tools) a "distro" simply refers to a particular assortment of applications married with a particularly compiled kernel, such that its "out-of-the-box" capabilities meets most of the needs of its particular end-user base. To provide a Unix-like environment, Linux distributions contain a set of Unix-like utilities and the libraries needed to support them. In full-featured distributions these are generally taken from the GNU Operating System . Distributions optimized for size tend to use more compact alternatives like Busybox , Uclibc or Dietlibc . There are currently over three hundred Linux distribution projects in active development, constantly revising and improving their respective distributions. One can distinguish between commercially-backed distributions, such as Fedora ( Red Hat ), SUSE Linux ( Novell ), Ubuntu ( Canonical Ltd. ) and Mandriva Linux and community distributions such as Debian and Gentoo . Usually, the procedures for assembling and testing a distribution prior to release are more elaborate the bigger the user base for the distribution is. HISTORY Before the first Linux distributions, a would-be Linux user was required to be something of a Unix expert, not only knowing what libraries and executables were needed to successfully get the system to boot and run, but also important details concerning configuration and placement of files in the system. Linux distributions began to appear soon after the Linux kernel was first used by individuals outside the original Linux programmers. They were more interested in developing the Operating System than they were in application programs, the user interface, or convenient packaging. Early distributions included:
SLS was not well-maintained, so Patrick Volkerding released a distribution based on SLS, which he called '' Slackware ''; released July 16 , 1993 http://www.slackware.com/announce/1.0.php. This is the oldest distribution still in active development. Users were attracted to Linux distributions as alternatives to the DOS and Microsoft Windows operating systems on the PC , Mac OS on the Apple Macintosh and Proprietary versions of Unix . Most early adopters were familiar with Unix from work or school. They embraced Linux for its stability, low (if any) cost, and for the availability of the Source Code for most or all of the software included. The distributions were originally simply a convenience, but today they have become the usual choice even for Unix or Linux experts. To date, Linux has proven more popular in the server market, primarily for Web and Database servers (''see also'' LAMP ), than in the desktop market. COMPONENTS A typical desktop Linux distribution comprises a Linux Kernel , GNU tools and libraries, additional software, documentation, a Window System , Window Manager , and a Desktop Environment . Most of the included software is Free Software / Open-source Software which is distributed by its maintainers both as compiled binaries and in Source Code form, allowing users to modify and Compile the original source code if they wish. Other software included with some distributions may be proprietary and may not be available in Source Code form. Many provide an installation system akin to that provided with other modern operating systems. '' Self-hosting '' distributions like Gentoo Linux , T2 and Linux From Scratch provide the source code of all software and include binaries only of a basic kernel, compilation tools, and an installer; the installer compiles all the software for the specific Microarchitecture of the user's machine. Package management See Also: Package management system Linux package formats Distributions are normally segmented into packages. Each package contains a specific application or service. Examples of packages include a library for handling the PNG image format, a collection of fonts, or a Web Browser . The package is typically provided as compiled code, with installation and removal of packages handled by a Package Management System (PMS) rather than a simple File Archiver . Each package intended for such a PMS contains meta-information such as a package description, version, and " Dependencies ". The package management system can evaluate this meta-information to allow package searches, to perform an automatic upgrade to a newer version, to check that all dependencies of a package are fulfilled and/or to fulfill them automatically. Although Linux distributions typically contain much more software than proprietary operating systems, it is normal for local administrators to install software not included in the distribution. An example would be a newer version of a software application than that supplied with a distribution, or an alternative to that chosen by the distribution (''e.g.'', KDE rather than GNOME or vice versa). If the additional software is distributed in source-only form, this approach requires local compilation. However, if additional software is locally added, the 'state' of the local system may fall out of synchronization with the state of the package manager's database. If so, the local administrator will be required to take additional measures to ensure the entire system is kept up to date. The package manager may no longer be able to do so automatically. Most distributions install packages, including the kernel and other core operating system components, in a predetermined configuration. Few now require or even permit configuration adjustments at first install time. This makes installation less daunting, particularly for new users, but is not always acceptable. For specific requirements, much software must be carefully configured to be useful, to work correctly with other software, or to be secure, and local administrators are often obliged to spend time reviewing and reconfiguring assorted software. Some distributions go to considerable lengths to specifically adjust and customize most or all of the software included in the distribution. Not all do so. Some distributions provide configuration tools to assist in this process. Note that such adjustments are typically site-specific and it is not possible for anyone, including a distribution's designer, to configure the software provided to meet individual requirements. As with all operating systems, Linux and its distributions require its users/operators/owners to perform system administration. Linux distributors differ from most operating system vendors in not claiming that "no administration is required." This honesty can worry potential users who have been told otherwise in marketing claims of other operating systems. By replacing ''everything'' provided in a distribution, an administrator may reach a 'distribution-less' state: everything was retrieved, compiled, configured, and installed locally. It is possible to build such a system from scratch, avoiding a distribution altogether. One needs a way to generate the first binaries until the system is ''self-hosting''. This can be done via compilation on another system capable of building binaries for the intended target (possibly by Cross-compilation ). See for example Linux From Scratch . CHOOSING A LINUX DISTRIBUTION Broadly, Linux distributions may be: # Commercial or non-commercial; # Designed for enterprise or for home usage; # Designed for servers, desktops, or embedded devices; # Targeted at regular users or power users; # General purpose or highly specialized toward specific machine functionalities, for example firewalls, network routers, and computer clusters; # Designed and even certified for specific hardware and computer architectures; # Targeted at specific user groups, for example through language Internationalization And Localization , or through inclusion of many Music Production or Scientific Computing packages. The diversity of Linux distributions is due to technical, organizational, and philosophical variation amongst vendors and users. The permissive licensing of free software means that any user with sufficient knowledge and interest can customize an existing distribution or design to suit his or her own needs. Technical variations include support for different hardware devices and systems or software package configurations. Other differences are motivated either by technical decisions, philosophical or even historical reasons. Some distributions specialize in use on desktops, servers or routers. Other criteria include security (and how often security updates are available), ease of package management and the number of binary packages available. There are tools available to help making the decision, such as several different versions of the Linux Distribution Chooser http://www.zegeniestudios.net/ldc/ http://www.tuxs.org/chooser/ http://desktoplinuxathome.com/distro.html and the universal package search tool, whohas.http://www.philippwesche.org/2004/programs/whohas/intro.html There are some easy ways to try out several Linux distributions before deciding on one. and VMware permit booting of LiveCD image files. In the case of VMware, this requires a specific virtual machine to be downloaded.http://www.vmwarez.com/2006/02/livecd-player-virtual-machine.html Emulating Ubuntu in Windows XP using the free VMware Player In QEMU, the functionality is already included. Details and interest rankings of Linux distributions are available on DistroWatch and a fairly comprehensive list of Live CDs is The LiveCD List . Some websites such as OSDir.com and OSVids.com offer screenshots and videos as a means to getting a first impression of various distributions. Each distro has its own merits and demerits, making selection of a distro a matter of matching needs and attitudes, with distro philosophy and software contents. Nevertheless, well-known Linux distributions include:
That multiple Linux distributions peacefully coexist severely limits the possibility of anti-competitive lawsuits comparable to those filed in the United States V. Microsoft and European Union V. Microsoft trials; these lawsuits exposed the danger to a sole company that extends its Monopoly through Vendor Lock-in by controlling not only an operating system installed on the vast majority of computers but also an important collection of software that runs under that operating system. One inconvenience of this system is that the definition of a Linux operating system is somewhat unclear. Linux may be seen as either an operating system unto itself, or a family of operating systems, one for each distribution. The important point is that most Linux software is compatible across all major distributions, even at the binary level, and that only distribution-specific software will not work with another distribution. Demonstration The difficulty of quickly demonstrating Linux on the computer of a potential new user remained an obstacle until recently, slowing its adoption as a personal computing platform. However, Knoppix has pioneered the ability to run directly from a " Live CD " running entirely in RAM , rather than installing it to the Hard Drive . Other distributions have followed suit, and live versions are available for SUSE , Ubuntu , Mepis , and others. Some minimal distributions such as Tomsrtbt can be run directly from as little as 1 floppy disk without needing to change the hard drive contents. Linux User Groups , or LUGs, still provide the primary face-to-face forum for demonstration of Linux. Commercial exhibitions provide Linux demonstrations to potential new users, especially corporate buyers. The fastest approach is probably that of Workspot , which used VNC to provide a free Linux desktop demo online. Interdistribution issues The Free Standards Group is an organization formed by major software and hardware vendors that aims to improve interoperability between different distributions. Among their proposed standards are the Linux Standard Base , which defines a common ABI and packaging system for Linux, and the Filesystem Hierarchy Standard which recommends a standard filenaming chart, notably the basic directory names found on the root of the tree of any Linux filesystem. Those standards, however, see limited use, even among the distributions developed by members of the organization. Niche distributions The fictional Jesuxhttp://www.geocities.com/ResearchTriangle/Node/4081/ was a fake Christianity-inspired distribution that used the , and Ubuntu Christian Edition both bundle Bible-oriented applications and theological dictionaries in their main distributions. Other distributions are targeted at other specific niches such as the tiny embedded router distribution DD-WRT , the Ubuntu project to create Edubuntu for educational users, and KnoppMyth which wraps Knoppix around MythTV to ease building Linux-powered DVR s. INSTALLATION There are many ways to install a Linux distribution:
Anaconda , one of the more popular installers, is used by Red Hat Enterprise Linux , Fedora and other distributions to simplify the installation process. Installation on an existing platform Some distributions let the user install Linux on top of their current system, such as WinLinux . Linux is installed to the Windows hard-disk partition, and can be started from inside Windows itself. Similar approaches include CoLinux . Virtual Machine s (such as Virtual PC or VMware ) also enable Linux to be run inside another OS. The VM software simulates an isolated environment onto which the Linux system is installed. After everything is done, the virtual machine can be booted just as if it were an independent computer. Installation through an existing platform Most recently, a Windows installer for . The Windows installer for Debian (known internally as ''win32-loader'') is in the process of being integrated in official Debian CDs/DVDs. PROPRIETARY SOFTWARE Some specific proprietary software products are not available in any form for Linux. This includes many popular computer games, although in recent years some game manufacturers have begun making their software available for Linux. For example, Epic Games sells a Linux version of its Unreal Tournament 2004 . This problem is also addressed by Emulation and API-translation projects like Wine and Cedega , which make it possible to run non-Linux-based software on Linux systems, either by emulating a proprietary operating system or by translating proprietary API calls (e.g., calls to Microsoft's Win32 or DirectX APIs) into native Linux API calls. OEM CONTRACTS Computer hardware is often sold with the operating system of a software Original Equipment Manufacturer (OEM) already installed. It is uncommon for this operating system to be Linux, even though the portability features of Linux mean that it can be installed on most machines. In the case of IBM PC Compatible s the OS is usually Microsoft Windows ; in the case of Apple Macintosh computers it has always been a version of Apple's OS, currently Mac OS X ; Sun Microsystems sells SPARC hardware with Solaris installed; video game consoles such as the Xbox , PlayStation , and Gamecube each have their own proprietary OS. That Linux is not installed by default on most computer hardware limits its market share: consumers are unaware that an alternative exists, they must make a conscious effort to use a different operating system, and they must either perform the actual installation themselves, or depend on support from a friend, relative, or computer professional. However, it is actually possible to buy hardware with Linux already installed. on the keyboard). Terra Soft sells Macintosh computers and PlayStation 3 consoles with Yellow Dog Linux installed. It is more common to find embedded devices sold with Linux as the default manufacturer-supported OS, including the Linksys NSLU2 NAS device, TiVo 's line of personal video recorders, and Linux-based cellphones, PDAs, and portable music players. Consumers also have the option of obtaining a refund for unused OEM operating system software. The s) and the DGCCRF branch of the French government filing several complaints against bundled software. SEE ALSO
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