Linux distribution |
A Linux distribution is a Unix-like operating system comprising the Linux kernel plus most of the GNU operating system(almost always but necessarily), other assorted free software, open source, and possibly proprietary software software.
Companies such as Red Hat, SUSE and Mandriva, and community projects such as Debian, Ubuntu Linux, Gentoo Linux, and the entirely-free Ututo, assemble and test the software before releasing their distribution. There are currently over three hundred Linux distribution projects in active development, revising and improving their respective distributions.
= 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 in application programs, the user interface or convenient packaging.
Early distributions included:
None of these distributions were well maintained, so Patrick Volkerding released a distribution based on SLS, which he called Slackware ; this is the oldest distribution still in active development.
Linux distributions attracted users as an alternative to the Microsoft Windows operating systems on the IBM PC compatible and to Mac OS on the Apple Macintosh. Most early adopters were used to Unix from work or school. They embraced Linux for its stability, low (if any) cost, and for the inclusion 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 resort even for Unix or Linux gurus. To date Linux has proven more popular in the server market, primarily for World Wide Web and Database servers ( see also LAMP (software bundle)), than in the desktop market.
= Composition =
The Linux kernel, GNU, and most of the additional software making up a typical Linux distribution are free software and open source software, distributed by its maintainers both as pre-compiled binaries and in source code form, allowing users to compile the original source code into binary or executable form if they wish.
A Linux distribution almost always offers compiled versions of the Linux kernel, GNU system libraries and assorted programs that make up the rest of an operating system. Many provide an install program / procedure akin to that provided with other operating systems which are distributed in binary form ( e.g. , Solaris Operating Environment, Microsoft Windows, etc.). Other self-hosting distributions ( e.g. , Gentoo Linux, etc.) provide the source code of all software but only binaries of a basic kernel, compiler tools ( e.g , a compiler, Make utility and so on), and an installer; the installer compiles all the software specifically for the CPU Architecture of the user s machine.
Distributions are normally segmented into packages , each holding a specific application or service; one package may hold a library for handling PNG images, another may contain a number of fonts, while a third may supply a web browser.
In addition to providing packaged compiled code, most distributions offer tools for installation/removal of packages that are more powerful than simple file archiver. This software is said to be the package management system (PMS) of the distribution. Each package intended for such a PMS contains meta-information like description, version, Dependency (computer science) , etc. The package management system can evaluate this meta-information, to allow package searches, automatic upgrade to newer versions, checking that all dependencies of a package are fulfilled and/or fulfilling them automatically, and more. Package management systems include:
*RPM Package Manager — now RPM Package Manager, but originally Red Hat Package Manager, originally from Red Hat but now used by many other distributors as well *deb (file format) — Debian package, originally from Debian but also used by others *tgz or tar.gz — standard TAR file format + gzip, possibly with some extra control files — used by Slackware and others, or sometimes when distributing very simple handmade packages *ebuild — the file containing information on how to retrieve, compile, and install a package in Gentoo s Portage (software) system using the command emerge. Typically these are source-primary installs, though binary packages can be installed in this fashion as well. *src — building the packages from source (often binary packages are provided in parallel on many systems).
Although GNU/Linux distributions typically contain much more software than proprietary operating systems, it is normal for local administrators to install software not included with 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 user will be required to take additional measures to ensure the entire system is kept up to date, that all required patches are installed, etc. 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 is less daunting, particularly for new users, but not always acceptable. Since much software must be carefully configured to be useful, to work correctly with other software or to be secure, local administrators will often be obliged to spend time reviewing and reconfiguring assorted software. Some distributions go to considerable lengths to specifically adjust all (or some) of the software they include to their particular distribution (location of particular files and so on), but not all do so. Some distributions provide configuration tools to assist in this process, but, again, not all. Note that such adjustments may be required for a particular site and that it is not, in principle, possible for anyone including a distribution s designer to preconfigure the software provided to meet individual requirements. As with all operating systems, Linux and its distributions impose a system administration obligation on its users/operators/owners. 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.
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, bypassing any distribution altogether, but one needs a way to generate the first binaries until the system is self-hosting ( i.e. , has a bootable kernel, and compilation tools to generate more binaries). This can be done via compilation on another system capable of building binaries for the intended target (possibly by cross-compilation). See [http://en.tldp.org/LDP/lfs/LFS/index.html Linux From Scratch Guide] for instructions.
=Choosing Linux distributions=
Read Comparison of Linux distributions or List of Linux distributions to help make up your mind about which distribution to use.
These are the most popular according to [http://www.distrowatch.com/ DistroWatch] and therefore the most common distributions of GNU/Linux for PCs and other workstations, listed alphabetically.
They can differ in the following ways:
You may want to try the [http://www.zegeniestudios.net/ldc/index.php Linux Distribution Chooser] to help you decide.
Sometimes the variety of distributions causes a fragmentation among Linux users. While the general philosophy of Linux has to do with free and open software, it is believed that each distribution, except its unique differences, has also its own philosophy which is good for a user but isn t for another. Each distro therefore has formed its own micro-community inside the wider Linux community, and the community istself influences the philosophy of the distro. Members of each community sometimes see to the other Linux users the way that the inhabitants of an island see the natives of a neighbour island.
For example, a distribution who comes with a strong philosophy which is generalised beyond the philosophy of software, is Ubuntu. Slackware s philosophy is about having only stable components, and not caring much on graphical interfaces. The general corpus of Slackware users don t think high of RedHat, etc.
=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 Application binary interface and packaging system for GNU/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.
= See also =
*List of Linux distributions *Comparison of Linux distributions *MiniLinux *GNU/Linux naming controversy
= Notes =
Linux distrubutions may also be referred to as GNU/Linux distributions, though the latter may more often refer to the Debian system. The term distribution often suffices and is at least sufficent enough to distinguish free operating systems like Linux/GNU/BSD from commercial operating systems such as Microsoft Windows or Apple Mac OS X. The term distribution is often informally shortened to distro.
= External links =
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