Linux-Distribution
A Linux distribution is a collection of programs that contain the Linux kernel as the operating system and a number of applications. Almost every Linux distribution is put together a package management around, ie that all components are present as software packages and install via the package manager to uninstall and can also update. Software packages are kept in so-called to online repositories.
A distribution is compiled by a Linux distributor, thus requires the transfer and dissemination is expressly permitted by third parties by the fact that the Linux kernel and the majority of the programs are free software, and. The distributor chooses any software from the entire pool of available free software, this fits more or less on his ideas, package this package for the administration of his choice and provides the result, the Linux distribution, all over the world or customers. Only a few programs are written by the distributor itself, such as the Debian installer. The distributor can be a company or a group of globally distributed volunteers and he can offer commercial support.
- 3.1 smartphone distributions
- 3.2 live systems
- 4.1 Multi-boot
- 4.2 virtualization
- 5.1 Compatibility between the distributions
- 5.2 standardization approaches
Concept
Task of a Linux distributor is putting together a usable for the intended purpose overall system from source code and partly proprietary, binary software components of other software vendors to then offer this as a so-called distribution. The central part of this case form the Linux kernel itself, as well as system programs and libraries. Depending on the intended use of the distribution various application programs are added (such as web browsers, office applications, graphics programs, media players, etc.).
Because Linux distributions include the application programs, they usually have a very large selection of installable applications. This is, put in the conceptual contrast to other operating systems such as Windows or Mac OS X, which in addition to the operating system itself is only a few applications for the integration of programs by external providers, so-called ISVs.
A distinguishing feature of the distributions are mutually supporting periods or the update cycles. There are distributions for which the same version is powered by more than 7 years with updates (eg RHEL) is advised while in others after half a year to an update to the next version. Other distributions have no versions, but are so-called Rolling Releases, renews permanent system components and applications.
Other differences between the distributions can be seen with respect to the licensing policy. Some distributions integrate exclusively Free Software, distributed binary proprietary software will not be allowed in such a distribution. Other integrate proprietary software.
Other objects of the distributions are the adaptation of the programs ( by patching ), addition of own program developments (especially the installation and configuration of the system such as apt, Synaptic, YaST ) and (with a few exceptions, such as Gentoo ) compilation and packaging (. deb. rpm) of the programs. The provision of additional programs and updates is typically done centrally via a repository which is synchronized via a package management system with the operating system.
Although Linux operating systems in the form of a distribution is the most common variant by far, one of Linux operating without a pre- distribution is possible, as the Linux From Scratch Project shows.
Composition
In addition to the Linux kernel usually consists of a distribution of GNU software environment that provides the basic foundation system with the many system services (so-called daemons ) and various applications that are expected from a Unix-like system. Distributions, which are also or only meant for desktop systems usually have an X Window System. Such is required for the execution of a graphical user interface. On this basis, usually is a desktop environment such as Gnome or KDE Software Compilation available, which brings besides the pure UI still a variety of application programs.
In addition adds a distributor usually in numerous other applications. These are, for example, office suites, multimedia software, editors, e- mail programs, browsers, but also server services. In addition, most software development tools such as compilers or interpreters find and editors.
Many software components (eg, the compiler GCC), of which there are Linux distributions that come from the older GNU Project. This had placed himself before the development of Linux, the task of developing an alternative to the commercial Unix operating systems. Since the linux kernel of the GNU Project, GNU Hurd, with the appearance of Linux was still in development, the Linux kernel has been used as an available substitute. Hence the double name GNU / Linux is a distribution for familiar (eg Debian).
There are also Linux distributions that completely do away with the GNU software units or an X Window system and use alternative software in their place. These distributions behave, such as FreeVMS or Cosmoe, sometimes not nearly like a Unix system.
Distribution
While proprietary operating systems are often sold via the retail, this is the exception rather in Linux distributions. Most distributions can be downloaded free of charge from the website of the provider today. These are funded by donations, via paid support or even just on the participation of volunteers. Only relatively few distributions are developed by for-profit companies and are partially available through retail. Many Linux distributions are also purchased by customers unnoticed, as firmware on a device or even in larger machines or systems. It may be, for example, to machine tools, automobiles, household appliances, PLCs, measuring apparatus, mobile phones, modems, digital cameras, NAS or TV.
History
Since Linux is just an operating system kernel, additional software is required to obtain a usable operating system. For this reason, the first Linux distributions already came on shortly after the GPL licensing of Linux, as users who do not belong to the direct developer circle, began to use Linux. The first distributions were here the goal is to focus the system, for example with the software from the GNU project to an operational operating system. Among them were MCC Interim Linux, which was published on the FTP servers of the University of Manchester in February 1992, TAMU, which was created by some programmers Texas A & M University at about the same time, and Soft Landing Linux System ( SLS). The first commercially available on CD distribution was 1992, the Yggdrasil Linux, developed by Adam J. Richter. On 16 July 1993 Patrick Volkerding released the Slackware distribution. It is the oldest still active Linux distribution.
The first user still knew free software from before the 1980s, and appreciated Linux because they again had the utilization rights to the software they use. Subsequent users were Unix users, the Linux first primarily private inserting and rejoiced especially about the low price. Had been created only for convenience, the first distributions, they are now the usual way for users as well as developers to install a Linux system. The Linux distributions are nowadays developed and operated by both groups of developers as well as companies or non-profit projects.
The question of which distributions are particularly popular, can be answered only with difficulty. In the German-speaking world, especially Ubuntu, Debian, openSUSE and Knoppix are mentioned more frequently outside the IT press. In addition, Fedora would be mentioned, that of the US-listed company Red Hat is developed.
Types of distributions
Since distributions are practically their own products, this market compete and try the one hand, to distinguish from each other, but on the other hand, to leave also other distributions not to great advantage. Therefore, although all distributions differ, but there is little something for which not could be adapted to any distribution. This excludes only special systems, such as software in the embedded space.
Some distributions are optimized for a use case, so there are about systems specially designed for use in educational institutions with specialized software for this purpose and in most cases a Terminal Server system, leaving only a powerful machine is required and otherwise older hardware is strong enough. Examples include Edubuntu or skolelinux. Similarly, there are systems specifically for obsolete computers that have limited functionality and provide low system requirements. Examples include Damn Small Linux or Puppy Linux, which have a circumference of only 50 or 100 MB.
Smartphone distributions
For smartphones, there are specific Linux distributions. They offer in addition to telephony and text messaging features various PIM, navigation and multimedia features. The operation is usually done via multi-touch or with a stylus. These Linux distributions are usually developed by a consortium of firms or a single firm. In part, they differ greatly from the otherwise classic desktop and server distributions. Unlike in the embedded field the Smartphone distributions but are not limited to a particular device. They serve as the operating system for devices of very different model lines that are often offered by various manufacturers.
Representatives are Android, Bada, Maemo, Mobi Linux and WebOS. The architecture of such smartphone Linux distributions such as Android, has in addition to the Linux kernel only little in common with traditional Linux distribution concepts. It is also typically used only a small part of the usual GNU software environment and tools. Since Android is not entirely free software (including but released Google shares only under the GPLv2 -incompatible Apache license ) and Google's Android Market, the use of uncontrolled proprietary binary software allows, Richard Stallman and the FSF Android is very critical and recommend the use alternatives. Some commonly used with Linux UNIX - like services, libraries and tools have been replaced by Java Runtime -based services and tools, In Android, making porting existing native Linux applications or libraries can be difficult. The programming interfaces newly defined can, however, emulate or implement on traditional Linux systems.
While the market share of previously widespread mobile OS platforms like Apple's iOS, Microsoft's Windows Mobile and Nokia's Symbian OS fell, Android gained market share. Since late 2010, Linux - based distributions have taken the lead in the fast- growing smartphone market. They exhibited together in July 2011 to a market share of at least 45 %. While the Linux-based smartphone Bada distributions or WebOS could not prevail on the market (as of 2012), the demand for Google's Android has continued to grow. In August 2012, the Android distribution has reached a market share of 68.1 %.
Live systems
A special form live systems that can be booted from CD, DVD, USB and other media. Was it here first only at specialized distributions, which should demonstrate the capabilities of Linux, it is now one rigueur among Linux distributions offer the standard scale in the form of a live CD or (more rarely) DVD. Some of these systems can also be installed directly from the CD.
Live systems can be started as a full Linux without writing to the hard disk and without changing the existing configuration of a computer. Thus, the corresponding Linux distribution can be safely tested on a computer. Live systems are also ideal for data recovery and system analysis, since they are independent of the configuration of the existing system and so also of possible infections caused by worms and viruses can not be affected.
Linux distributions with another OS
Most Linux distributions can be installed on the same hardware in parallel to other operating systems. As such, for example, come another Linux distribution, another unixoides operating system such as Mac OS X or Solaris, or even a Windows considered. In principle, two approaches can be distinguished:
Multi-boot
In a multi-boot configuration, two or more operating systems are installed in parallel on different hard drive partitions. Installers modern Linux distributions can usually detect currently installed operating systems and autonomously set up a multi-boot configuration. After installation, you can choose when booting a boot loader or boot manager to start the operating system.
Virtualization
If the operating systems often used simultaneously, may offer rather a virtualization solution. This requires distinguishing the host and guest system. The former is actually physically installed on the hardware. Within its virtualization software such as VirtualBox or KVM is used. This emulates the guest system provides all the necessary hardware or by a security system direct access to the actually present hardware of the computer. Since it is necessary in such a configuration for the simultaneous operation of both systems, there may be loss of speed.
Differences between individual distributions
Even leaving aside special distributions, are also popular Linux distributions differ in some points. Important initially setting features form tools for installation such as partitioning tools. These are based mostly on the number of users of a distribution. While beginners example, only few options are offered, so as not to overwhelm these other distributions to more advanced users who prefer more configuration options already in the installation stage is set. After installation, set this difference, based on the user group, usually in the amount of configuration programs continued. To provide some distributions of mature graphical tools for editing configuration files, while others only provide for the direct processing of such. However, the latter often offers the possibility of refining adapt to their own needs, sets in return but they require greater knowledge of the user.
Compatibility between the distributions
The differences between the distributions appear often on their compatibility.
Early in the history of the distributions created concepts to simplify the installation of additional software. Most software should be provided in the form of compiled packages and a mechanism be provided that can resolve functional dependencies between installed and reloaded packages. The resulting package management systems work with each own package formats, such as RPM or dpkg. Many Linux distributions have their own management software with its own binary packages that are to other distributions partially incompatible.
The criticism of the principle of Linux distributions is, among other things at this point. Since not every software project and not every software developer has the knowledge and resources to provide software for every single Linux distribution, only the source code is often published. From the published source code for generating executable applications, but is potentially a complicated and error- prone process, which may be too complicated for many users. This then often remain dependent and limited to the software supplied by your distribution. However, the Bereitststellung the source code as a software delivery method is for commercial software vendors who want to deliver software binary, not an option, so they must use the set of distributions and their packet formats with specific packages, what a little extra effort means. In a corporate environment, therefore, has only a limited range of distributions a chance as general working platform.
Standardization approaches
In order not to diverge the distributions on, the Free Standards Group (now Linux Foundation ) founded with the aim to promote appropriate standards between distributions. The most popular one is the Linux Standard Base for the promotion of the binary compatibility of the distributions. The LSB is thereby converted from the various distributions differ strongly. It defines matching binary interfaces ( "ABI " called for Application Binary Interface), some details of the internal structure and a package system (in RPM) that must be supported for installing third-party software.
The practical significance of these rules is rather limited. The unilateral establishment on the RPM package format is casting some doubts after has gained in recent years by Ubuntu or Linux Mint the dpkg format a wide distribution. Because most distributions use dpkg directly based on Debian, which are often packages in other distributions, which are also based on Debian install. On the other hand, all set of Fedora ( or rather Red Hat Linux), openSUSE and Mandriva distributions derived on RPM. It is quite possible, with some restrictions - eg using the openSUSE Build Service - create RPM packages that can be used on all of these distributions.
Another standardization represents the Filesystem Hierarchy Standard, which should enable a common naming some file and directory names and a matching structure of the base directories. However, details are not covered here, which previously produced the incompatibilities. Other problems arise only through the tight integration of applications in the system directory tree. It is required by the Linux Standard Base.
Because the standards were not sufficiently implemented, announced in December 2006, Ian Murdock, then technical director of the Free Standards Group, as part of the Linux Standard Base, a further initiative to simplify the installation of software. Essence of the method is a programming interface that is placed over the package management of your distribution. This interface can provide standard functionality for the software package and implement them for the particular distribution. So it should be possible to share files and dependencies to the distribution 's package management system. A practical implementation of this, but there was not at least until the beginning of 2013.
Alternative approaches for program distribution
There are several alternative approaches to the model of centralized software distribution via the distributions and their repositories. Projects such as Autopackage, Zero Install or Klik successor Portable Linux Apps try a uniform, but decentralized, independent distribution, software binary distribution ability to create, but until now could achieve virtually no relevant distribution or support of the Linux community.
A step in this direction was the introduction in 2011 of a software center in Ubuntu, after the model of the App Store by Apple in order to increase the number of applications significantly, since the distribution model scales is limited.
2012 also stressed kernel developer Ingo Molnar the need for the provision of such a decentralized, efficient scaling and distribution independent software distribution method; the absence of such a mechanism is one of the core problems of the Linux desktop.