Wikiprojekt:Informatyka/en/Linux

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Linux - rodzina uniksopodobnych systemów operacyjnych, używajaca jądra Linux. Kompletny system operacyjny zawierający narzędzia i biblioteki z projektu GNU jest niekiedy nazywany GNU/Linux.

W okresie od 1984 do 1991 większa część dzisiejszego systemu operacyjnego była rozwijana w ramach projektu GNU. Po 1991, programiści tworzący jądro Linuksa jak też inni entuzjaści zaczęli rozwijać inne komponenty systemu. W końcu lat 90. Linux zdobył również uznanie i wsparcie dużych firm, jak IBM,^[1] Sun Microsystems,^[2] Hewlett-Packard,^[3] i Novell.^[4]

Linux jest sztandarowym przykładem wolnego oprogramowania i modelu rozwoju zgodnym z ideą otwartego kodu źródłowego. Stanowiący podstawę systemu kod źródłowy jest dostępny dla każdego z licencją zezwalającą na używanie, modyfikację i rozpowszechnianie. Część oprogramowania dla Linuksa jest również rozprowadzana na innych, zamkniętych licencjach.

Spis treści 1 Historia 1.1 Projekt GNU 1.2 Rozwój Linuksa 1.3 Linux dzisiaj 1.4 Kod źródłowy 1.5 Udział rynkowy i wzrost popularności 2 Nazwa Linuksa 2.1 Etymologia 2.2 Wymowa 2.3 Pisownia w języku polskim 2.4 GNU/Linux 2.5 Znak handlowy Linux 3 Prawo autorskie i licencjonowanie 3.1 SCO litigation 4 Philosophy 4.1 Free software and open source 4.2 Interoperability 4.3 Portability 4.4 Community 4.5 Commercialization 5 Distribution 5.1 Role 5.2 Choosing a distribution 5.3 Installation 5.4 OEM Contracts 6 Interface 6.1 Command line interface 6.2 X window managers 6.3 Desktop environments 7 Applications 7.1 Desktop 7.2 Gaming 7.3 Servers, supercomputers and embedded devices 7.4 Software development 8 Comparisons with other operating systems 8.1 Comparison of Windows and Linux 9 References 10 Notes 11 See also 12 External links

[edytuj] Historia

[edytuj] Projekt GNU

Historia Linuksa jest ściśle powiązana z historią projektu GNU. Plan projektu został ogłoszony publicznie przez Richarda Stallmana w 1983. GNU miało być kompletnym uniksopodobnym systemem operacyjnym składającym się wyłącznie z wolnego oprogramowania. Prace nad pisaniem kodu rozpoczęto w styczniu 1984. Do początku lat 90. w ramach projektu powstała większość niezbędnych komponentów systemu: biblioteki, kompilatory, edytory tekstu i powłoki systemowe. W ten sposób zasadnicza część GNU była prawie gotowa. Nakładka graficzna X Window System mogła służyć jako zewnętrzna warstwa systemu operacyjnego, lecz nadal brakowało części niskopoziomowej, na którą składają się: jądro i sterowniki urządzeń. W 1990 projekt GNU rozpoczął rozwijanie własnego jądra GNU Hurd, opartego na mikrojądrze Mach, ale praca okazała się nadzwyczaj trudna i postępowała powoli. Do dzisiaj jądro Hurd nie uzyskało dostatecznej funkcjonalności i używane jest przez nielicznych.^[5]

W 1991, studiujący na Uniwersytecie Helsińskim Linus Torvalds zaczął pisać jądra Linuksa.^[6] Ideą Linusa było stworzenie jądra, które zastąpiłoby nie do końca wolnego Miniksa. Jądro Linuksa było początkowo zależne od oprogramowania użytkowego Miniksa, ale dzięki pracy programistów wkrótce dopracowano narzędzia projektu GNU, tak aby mogły działać w tym środowisku. W ten sposób Linux zapełnił ostatnią brakującą lukę w stworzeniu kompletnego, w pełni funkcjonalnego systemu operacyjnego, składającego się wyłącznie z wolnego oprogramowania.

[edytuj] Rozwój Linuksa

Oprogramowanie GNU i jądro Linuksa ustanowiły bazę systemu operacyjnego, który od tego czasu był wzbogacany przez licznych programistów społeczności wolnego oprogramowania. Do znaczących osiągnięć można zaliczyć:

• Zainicjowanie projektu KDE środowisko graficzne przez Matthiasa Ettricha w październiku 1996, a następnie alternatywnego środowiska GNOME przez Miguela de Icaza w sierpniu 1997. Oba środowiska bazowały na systemie okien X Window System rozwijanym przez MIT. Dzięki wygodnym nakładkom graficznym, takim jak KDE i GNOME, Linux zagościł na komputerach biurkowych mniej zaawansowanych użytkowników.
• Udostępnienie kodu źródłowego przeglądarki internetowej Netscape Navigator 31 marca 1998, które zainicjowało projekt Mozilla i ostatecznie doprowadziło do narodzin popularnej przeglądarki Mozilla Firefox.

• Wydanie pakietu StarOffice przez Sun Microsystems, który w czerwcu 2000 stał się bazą dla wolnodostępnego pakietu biurowego OpenOffice.org, co stanowiło znaczące wydarzenie dla społeczności otwartego oprogramowania.
• Komercyjne zainteresowanie Linuksem:^[7]
  • powołanie Open Source Initiative w lutym 1998,
  • ogłoszenie przez Oracle Corporation w lipcu 1998, że wyda port jej flagowej bazy danych dla Linuksa i będzie oferować dlań wsparcie,
  • pierwsze oferty publiczne firm Red Hat 11 listopada 1999 i VA Linux miesiąc później, które stały się bańką spekulacyjną,
  • wielkoskalowe wsparcie ze strony giganta technologicznego IBM, który zapowiedział wydanie milionów dolarów na Linuksa, zatrudniając w 2005 blisko 300 programistów jądra Linuksa i od 2003 organizował prawną obronę w sprawie SCO kontra Linux odpierając ataki SCO, utrzymującej że posiada prawa autorskie na znaczącą część kodu źródłowego jądra,
  • wykupienie w październiku i listopadzie 2003 firm Ximian i SUSE przez Novella.

[edytuj] Linux dzisiaj

Obecnie Linux występuje w licznych zastosowaniach, od systemów wbudowanych do superkomputerów i zyskał dużą popularność na serwerach internetowych wraz ze znanym pakietem aplikacji LAMP. Linus Torvalds nadal kieruje rozwojem jądra. Richard Stallman przewodzi Free Software Foundation, która koordynuje rozwijanie komponentów GNU. Wreszcie, indywidualni programiści i firmy tworzą pozostałe aplikacje spoza GNU. Programy te reprezentują wielką bazę rozwiązań, począwszy od modułów jądra, poprzez biblioteki i na aplikacjach użytkowych skończywszy. Dystrybutorzy Linuksa łączą jądro, aplikacje GNU i spoza GNU z dodatkowym oprogramowaniem do zarządzania pakietami i wydają całość w formie dystrybucji Linuksa.

[edytuj] Kod źródłowy

Wykonane w 2001 roku badanie dystrybucji Red Hat Linux 7.1 wykazało, że składało się na nią 30 milionów linii kodu źródłowego. Przy użyciu modelu COCOMO oceniono, że napisanie tego kodu wymagało około ośmiu tysięcy roboczolat nakładu. Według autorów badania, gdyby całe to oprogramowanie rozwijać w tradycyjnym modelu oprogramowania komercyjnego w Stanach Zjednoczonych, kosztowałoby to 1,08 miliarda dolarów.^[8]

Większość kodu (71%) było napisane w języku C, ale w użyciu było też wiele innych języków, m.in. C++, LISP, asembler, Perl, Fortran, Python i różne skrypty powłok uniksowych. Nieco ponad połowa kodu była objęta licencją GPL. Sam kod jądra Linuksa zajmował 2,4 miliona linii, co stanowiło 8% dystrybucji.^[8]

W późniejszym badaniu takiej samej analizie poddano dystrybucję Debian w wersji 2.2^[9] Składała się ona z ponad 55 milionów linii kodu źródłowego, a koszt jej wyprodukowania konwencjonalnymi metodami został oceniony na 1,9 miliarda dolarów.

[edytuj] Udział rynkowy i wzrost popularności

Wiele badań ilościowych nad otwartym oprogramowaniem skupia się na zagadnieniu udziału rynkowego i niezawodności; często badania te dotyczą Linuksa.^[10] Rynek Linuksa rośnie w szybkim tempie; przychody związane z tym systemem działającym na serwerach, komputerach biurkowych i sprzedawanym oprogramowaniem są szacowane na 35,7 miliarda dolarów w 2008.^[11] Oczywiście udziału Linuksa nie można oceniać wyłącznie w kategorii przychodów materialnych, ponieważ znaczna część dystrybucji Linuksa i oprogramowania jest darmowa i przeznaczona do nieograniczonej dystrybucji. Popularność na komputerach osobistych jest słabsza niż na rynku serwerów; w zależności od źródła oceniana jest w przedziale od 0,3% do 3%. Według badania firmy International Data Corporation 25% serwerów i 2,8% komputerów osobistych działały pod kontrolą Linuksa w 2004 roku.^[12]

Linux Online uważa, że przyczyną małej popularności Linuksa u przeciętnych użytkowników jest to, że redaktorzy znanych czasopism komputerowych nie dysponują odpowiednim doświadczeniem w korzystaniu z tego systemu.^[13] Ponadto istotnymi barierami popularyzacji są koszty związane ze zmianą istniejącego systemu operacyjnego i brak wsparcia dla niektórych komponentów sprzętowych i aplikacji dostępnych wyłącznie na platformę Microsoft Windows. Jednakże, biorąc pod uwagę stan z początku 2007 roku, osiągnięto znaczny postęp w kompatybilności sprzętowej. Wiele komponentów jest rozpoznawanych automatycznie i działają dobrze w wielu dystrybucjach. Zwolennicy systemu przypisują relatywny sukces Linuksa wysokiemu poziomowi bezpieczeństwa i niezawodności,^[14] niskim kosztom i brakowi zagrożenia uzależnieniem od dostawcy (ang. vendor lock-in).^[15]

[edytuj] Nazwa Linuksa

[edytuj] Etymologia

Sama nazwa pochodzi ze zbitki słów Linus (będącego imieniem twórcy) i Unix. Nie przyjęła się proponowana przez Torvaldsa nazwa Freax. Nazwa "Linux" informuje także o tym, że nie jest to system Unix: Linux Is Not UNIX.

[edytuj] Wymowa

W 1992, Linus Torvalds wyjaśnił jak się wymawia Linux w artykule Usenetowym,^[16] jednak ma on znaczenie głównie dla osób anglojęzycznych; dla Polaków wymowa tego słowa jest naturalna, zgodna z ogólnymi zasadami (/ˈlɪnʌks/). Dostępne są również nagrania dźwiękowe samego Linusa wyjaśniające po angielsku i szwedzku jak wymawia on Linux.^[17].

Należy podkreślić, że spotykana czasem w języku polskim wymowa Linuch jest niepoprawna.

[edytuj] Pisownia w języku polskim

Rada Języka Polskiego zaleca następującą pisownię nazwy "Linux" przy odmianie przez przypadki M: Linux, D: Linuksa, C: Linuksowi, B: Linuksa, N: Linuksem, Msc: Linuksie, W: Linuksie!

Zdania na ten temat są jednak podzielone nawet wśród językoznawców;^[18] zgoda panuje jedynie co do tego, by w miejscowniku pisać "Linuksie".

[edytuj] GNU/Linux

Zobacz więcej w osobnym artykule: GNU/Linux naming controversy.

Nazwa systemu Linux pochodzi od nazwy jego jądra. Ponieważ większość dystrybycji Linuksa używa oprogramowania z projektu GNU, Free Software Foundation uważa te dystrybucje za "warianty" systemu GNU, sugerując aby nazywano je GNU/Linux bądź system GNU oparty na Linuksie.^[19] Jednakże media i większość użytkowników używa słowa Linux dla całej rodziny systemów. Część twórców dystrybucji używa nazwy łączonej, na przykład Debian GNU/Linux należąca do projektu Debian, ale znajomość terminu GNU/Linux jest ograniczona poza zaangażowaną społecznością wolnego oprogramowania. Linus Torvalds powiedział, że nazywanie systemu w ten sposób jest "po prostu śmieszne".^[20] Podział pomiędzy jądrem Linuksa a dystrybucjami na nim bazującymi i zawierającymi oprogramowanie GNU jest źródłem nieporozumień dla wielu nowych użytkowników i nazewnictwo nadal stanowi przedmiot kontrowersji.

[edytuj] Znak handlowy Linux

W Stanach Zjednoczonych, nazwa Linux jest znakiem towarowym zarejestrowanym na Linusa Torvaldsa.^[21] Początkowo, nazwa ta nie była w ogóle zarejestrowana, ale 15 sierpnia 1994 William R. Della Croce, Jr. zgłosił znak Linux do rejestracji i domagał się tantiemów od dystrybutorów Linuksa. W 1996 roku, Torvalds i zamieszane w sprawę organizacje wniosły pozew domagając się przyznania znaku towarowego Torvaldsowi. W 1997 roku proces zakończył się ugodą.^[22] Obsługę znaku powierzono Linux Mark Institute. Torvalds oświadczył, że zarejestrował znak wyłącznie aby udaremnić praktyki jak wyżej wymieniona, ale w 2005 roku został zobowiązany przez amerykańskie prawo znaków towarowych do aktywnej ochrony swojej własności. W wyniku tego, LMI wysłało listy do dystrybutorów Linuksa domagając się opłaty za korzystanie z nazwy i wiele z nich przystało na te warunki.^[23]

[edytuj] Prawo autorskie i licencjonowanie

Jądro Linuksa i większość oprogramowania GNU jest objęta licencją GNU General Public License (GPL), wersja 2. Jednym z wymogów GPL jest to, że

Licencja GPL wymaga, aby wszystkie rozpowszechnione modyfikacje kodu źródłowego and derived works były także nią objęte, i jest czasami nazywana licencją typu "share and share-alike", lub "copyleft". W 1997 roku, Linus Torvalds stwierdził: "Making Linux GPL'd was definitely the best thing I ever did."^[24] Inne oprogramowanie może używać innych licencji; wiele bibliotek używa GNU Lesser General Public License (LGPL), bardziej liberalnej wersji licencji GPL, z kolei X Window System używa Licencji MIT. Przed ponad dziesięcioma laty, Free Software Foundation ogłosiła, że chciała by uaktyalnić licencje GPL do wersji 3, z powodu zwiekszających się obaw w stosunku do patentów na oprogramowanie i systemu DRM.^[25] In particular, DRM is appearing in systems running copyleft software, a phenomenon known as "tivoization" per Tivo's use of DRM. Linus Torvalds has publicly stated he would not move the Linux kernel to GPL v.3, specifically citing the DRM provisions.Szablon:Fact

[edytuj] SCO litigation

Zobacz więcej w osobnym artykule: SCO-Linux controversies.

In March 2003, the SCO Group filed a lawsuit against IBM, claiming that IBM had contributed portions of SCO's copyrighted code to the Linux kernel in violation of IBM's license to use Unix. Additionally, SCO sent letters to a number of companies warning that their use of Linux without a license from SCO may be actionable, and claimed in the press that they would be suing individual Linux users. This controversy has involved lawsuits by SCO against DaimlerChrysler (dismissed in 2004), and AutoZone, and by Red Hat and others against SCO. Furthermore, it is currently disputed by Novell whether the SCO even owns the relevant Unix copyrights.

SCO's claims have been numerous and varied widely over time. As per the Utah District Court ruling on July 3, 2006; 182 out of 294 items of evidence provided by SCO against IBM in discovery have been dismissed.^[26]

[edytuj] Philosophy

[edytuj] Free software and open source

Zobacz więcej w osobnym artykule: Free software.

The primary difference between Linux and other contemporary operating systems, for example Microsoft Windows, Mac OS X, and other proprietary UNIX systems, is that the Linux kernel, the GNU userland, and other components are free software, which is also known as open source software. Linux is not the only such operating system, although it is the most well-known and widely used one; others include the BSD derivatives NetBSD, OpenBSD, and FreeBSD, as well as GNU adaptations for other kernels, such as GNU/Solaris and GNU/Hurd.

Free software is not necessarily free of charge, and there may also be non-commercial software which is free of charge but not free software. Free software is also not completely free of restrictions, with the only exception being software in the public domain; this is a virtue of the software license and the copyright retained by its authors which together provide the four freedoms:

• The freedom to use the software without restriction
• The freedom to study the software and its source code
• The freedom to modify the software and adapt it to one's needs
• The freedom to redistribute the software under certain precise conditions

Some free software and open source licenses are based on the principle of copyleft, a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license is used for the Linux kernel itself: the GNU GPL written by Richard Stallman.

One of the advantages of open source, as proposed by Eric Raymond and others,Szablon:Fact is that it allows for rapid software bug detection and elimination, which is important for correcting security exploits. This argument rejects the notion of security by obscurity.

Contributors to free software are not uniquely software developers, as exemplified by the GNOME and KDE projects; there are many non-development contributions needed, as is the case for any software product. Furthermore, the principles of free software and open source have had repercussions in other domains where collaboration is possible and the cost of making copies is marginal. Amongst the members of this open source culture are the Creative Commons movement initiated by Lawrence Lessig and the collaborative encyclopedia Wikipedia founded by Jimmy Wales.

[edytuj] Interoperability

Linux aims for interoperability with other operating systems, and by extension the software that runs under Linux aims for interoperability with other Linux and non-Linux software. The reasons for this are two-fold. First, from a free software perspective, interoperability provides the first out of four freedoms, by allowing users free choice of software and data formats whilst not restricting them as a result of that choice. Second, from a commercial perspective, Linux is an operating system underdog competing with mainstream operating systems, and it cannot rely on a monopoly advantage; in order for Linux to be a convenient operating system for users that is commercially viable, it must interact well with non-Linux computers.

A priority is placed on open formats, public specifications for data that are freely available and free to implement, with the goal being to remove dependences on single pieces of software. These contrast with closed formats, which are either poorly documented or not documented at all, and for which there exists no agreement between competing vendors. When standards exist for network communication protocols, data formats, and APIs, they contribute to the robustness and adoption of Linux. In some cases, free software projects are the reference implementation of these protocols, examples being the Apache HTTP Server,Szablon:Fact and the X.org implementation of the X Window System.

Examples of standard conformance include Mozilla Firefox which adheres strictly to World Wide Web Consortium recommendations, Jabber which formed the basis for the XMPP standard recognized by the Internet Engineering Task Force in the domain of instant messaging, and office productivity suites such as OpenOffice.org and KOffice which brought to light the recent OpenDocument standard. Linux systems also adhere to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.^[27][28][29]

In other domains, there are neither recognized standards nor organizations to manage them. The market is therefore split between software which attempts to interoperate as much as possible, and that which establishes market dominance through vendor lock-in, or the use of closed formats and communication protocols. Prime examples of the first category draw from the instant messaging war, which is ruled by multiprotocol software such as Gaim, Kopete, and Trillian. The second category of software is exemplified by Microsoft Office and its widely used closed file formats, and the Common Internet File System protocol which allow for files and printers to be shared between different computers on a Windows network.

In these cases, interoperability depends on reverse engineering, which requires a substantial investment on the part of developers. The legal status of reverse engineering varies from country to country; it may be illegal in the United StatesSzablon:Fact but legal in Europe, provided the goal is limited to interoperability.Szablon:Fact Today, as a result of reverse engineering, OpenOffice.org can read most .doc files, and Samba allows non-Windows machines to interact with a Windows network.

A further problem beyond reverse engineering is when interoperability is needed for a format or protocol that is technically encumbered by digital rights management or Trusted Computing, or legally restricted by software patents or laws such as the EUCD and DMCA.

[edytuj] Portability

Linux is a portable operating system, one that runs on a wide variety of hardware. It runs on a more diverse range of systems than any other operating system.^[30] One of the original goals of the GNU system was portability,^[31] and while the Linux kernel was originally designed only for Intel 80386 microprocessors, it now supports dozens of computer architectures. Linux runs on computers from the hand-held ARM-based iPAQ to the mainframe IBM System z9, in devices ranging from supercomputers to mobile phones, and has a foothold in the personal computer and business desktop markets. Specialized distributions exist for less mainstream architectures. The ELKS kernel fork can run on Intel 8086 or Intel 80286 16-bit microprocessors, while the µClinux kernel may run on systems without a memory management unit including the Apple iPod. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as the iMac and PowerBook, Palm PDAs, GameCube, Xbox and even the Playstation Portable.

[edytuj] Community

Linux is largely driven by its developer and user communities. Some vendors develop and fund their distributions on a volunteer basis, Debian being a well-known example. Others maintain a community version of their commercial distributions, as RedHat does with Fedora Core.

In many cities and regions, local associations known as Linux Users Groups (LUGs) seek to promote Linux and by extension free software. They hold meetings and provide free demonstrations, training, technical support, and operating system installation to new users. There are also many internet communities that seek to provide support to Linux users and developers. Most distributions and open source projects have a chatroom on the popular freenode IRC network that are open to anybody with an IRC client. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. Linux-based newsgroups are available via the Google Groups interface and also via news readers. Finally, every established free software project and Linux distribution has one or more mailing lists; commonly there will be a specific topic such as usage or development for a given list.

In French, a Linux user may be known as a "Linuxien"; there is no such corresponding term in English. /There is a term "Linuxoid" in russian./

[edytuj] Commercialization

Finally, although Linux is generally available free of charge, several large corporations have established business models that involve selling, supporting, and contributing to Linux and free software. These include IBM, HP, Sun, Novell, and RedHat. The free software licenses on which Linux is based explicitly accommodate and encourage commercialization; the relationship between Linux as a whole and individual vendors may be seen as symbiotic. The business model of commercial suppliers is generally dependent on charging for support, especially for business users. A number of companies also offer a specialized business version of their distribution, which adds proprietary support packages and tools to administer higher numbers of installations or to simplify administrative tasks.

[edytuj] Distribution

Zobacz więcej w osobnym artykule: Linux distribution.

[edytuj] Role

A particular feature of free software and open source operating systems such as Linux is that there is a clear separation between software production and software distribution. Free software projects, although developed in a collaborative fashion, are often produced independently of each other. However, given that the software licenses explicitly permit redistribution, this provides a basis for larger scale projects that collect the software produced by stand-alone projects and make it available all at once in the form of a Linux distribution. Even though some distributions may include non-free software, that software must still be available under a license that permits free redistribution, unless it is maintained by the distribution itself; otherwise, the individual vendor is responsible for both production and distribution.

A Linux distribution, commonly called a "distro", is a project that manages a remote collection of Linux-based software, and facilitates installation of a Linux operating system. Distributions are maintained by individuals, loose-knit teams, volunteer organizations, and commercial entities. They include system software and application software in the form of packages, and distribution-specific software for initial system installation and configuration as well as later package upgrades and installs. A distribution is responsible for the default configuration of installed Linux systems, system security, and more generally integration of the thousands of Linux-based software packages into a coherent whole.

A typical general purpose distribution includes: a boot loader such as LILO or GRUB, the Linux kernel, GNU libraries and tools, command-line shells, the graphical X Window System and an accompanying desktop environment such as KDE or GNOME, together with thousands of application software packages, from office suites to compilers, text editors, and scientific tools. Distribution-specific package management systems include RPM, dpkg, and Portage. As well as those designed for general purpose use, distributions may be specialized for different purposes including: computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Furthermore, some distributions deliberately include only free software. Currently, over three hundred distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.^[32]

[edytuj] Choosing a distribution

Linux distributions are numerous and diverse, and choosing between them can be a complicated process; it is often useful to compare Linux distributions. Each distribution is different, and the project goals address varying vendor and end-user needs. Broadly, Linux distributions may be: 1) commercial or non-commercial; 2) designed for enterprise or for home usage; 3) designed for servers, desktops, or embedded devices; 4) targeted at regular users or power users; 5) general purpose or highly specialized toward specific machine functionalities, for example firewalls, network routers, and compute clusters; 6) designed and even certified for specific hardware and computer architectures; or 7) targeted at specific user groups, for example through language internationalization and localization, or through inclusion of many music production or scientific computing packages.

Well-known Linux distributions include:

• Slackware, one of the first Linux distributions, founded in 1993, and since then actively maintained by Patrick J. Volkerding
• Debian, a non-commercial distribution maintained by a volunteer developer community with a strong commitment to free software principles
• Red Hat, maintained by the American company of the same name, which also provides a community version in the form of Fedora Core
• Mandriva, a Red Hat derivative popular in France and Brazil, today maintained by the French company of the same name
• SuSE, originally derived from Slackware with the system management software borrowed from Red Hat, maintained by the company Novell
• Gentoo, a distribution targeted at power users, known for its FreeBSD-like automated system of compiling all applications from source code
• Ubuntu, a rapidly growing desktop distribution maintained by the company Canonical that is derived from Debian
• Knoppix, a LiveCD distribution that runs completely from removable media and without installation to a hard disk
• Linspire, a commercial desktop distribution based on Debian, and once the defendant in the Microsoft vs. Lindows lawsuit over its former name.

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.

[edytuj] Installation

The most common method of installing Linux on a personal computer is by booting from a CD-ROM or DVD that contains the installation program and installable software. Such a CD can be burned from a downloaded ISO image, purchased alone for a low price or provided as a cover disk with a magazine, obtained as part of a box set, or in some cases shipped for free by request. A box set may also include manuals and additional proprietary software. Mini CD images allow Linux to be installed from a disk with a small form factor. As with servers, personal computers that come with Linux already installed are available from vendors including Hewlett-Packard and Dell, although generally only for their business desktop lines. Alternatives to traditional desktop installation include thin client installation and running directly from a Live CD. In a thin client installation, the operating system is loaded and run from a centralised machine over a network connection. In a Live CD setup, the computer boots the entire operating system from CD without first installing it on the computer's hard disk. Some distributions have a Live CD installer, where the computer boots the operating system from the disk, and then proceeds to install it onto the computer's hard disk, providing a seamless transition from the OS running from the CD to the OS running from the hard disk. On embedded devices, Linux is typically held in the device's firmware and may or may not be consumer-accessible.

[edytuj] 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 compatibles the OS is usually Microsoft Windows; in the case of Apple Macintosh computers it has always been a version of Apple's OS, currently OS X; Sun 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 pre-installed. Hewlett-Packard and Dell both sell general purpose Linux laptops,^[33] and custom-order PC manufacturers will also build Linux systems. Terra Soft sells Macintosh computers and Playstation 3 consoles with Yellow Dog Linux pre-installed. It is more common to find embedded devices sold with Linux as the default manufacturer-supported OS, including the Linksys NSLU2 router, 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 end user license agreement (EULA) for Apple and Microsoft operating systems gives the consumer the opportunity to reject the license and obtain a refund. If requesting a refund directly from the manufacturer fails, it is also possible that a lawsuit in small claims court will work.^[34] On February 15, 1999, a group of Linux users in Orange County, California held a "Windows Refund Day" protest in an attempt to pressure Microsoft into issuing them refunds.^[35] In France, the Linuxfrench and AFUL organizations along with free software activist Roberto Di Cosmo started a "Windows Detax" movement,^[36] which led to a 2006 petition against "racketiciels"^[37] (translation: software racketeers) and the DGCCRF branch of the French government filing several complaints against bundled software.

[edytuj] Interface

[edytuj] Command line interface

Zobacz więcej w osobnym artykule: Command line interface.

Linux includes a command line interface (CLI) as part of its Unix-like functionality. Distributions specialized for servers or administration may use the CLI as their only interface, for the absence of a graphical user interface (GUI) helps to minimize system resource consumption. As well, Linux machines can run without a monitor attached. In order for a user to access them, either remote X11 usage is necessary, or the CLI must be used via a protocol such as SSH or telnet. On local networks, remote X11 usage is generally acceptable, but over long distances the network latency can be intolerable.

In the early history of Linux, many operations required CLI usage. The advent of distributions dedicated to desktop and family have changed this. However, online manuals for Linux often mention a CLI-based solution to a problem, even if a GUI-based alternative exists. The CLI is universal in the Linux world, whereas GUIs can differ from machine to machine. It also facilitates interoperation between Linux and non-Linux machines which also have a CLI; OS X machines are one example. It is also easier for an expert to help a user via the CLI if the user need only copy and paste the advice into a terminal.

A well-designed GUI is easier to use for most computing tasks, but power users may still prefer the command line; scientists, engineers, and software developers are among the most frequent users. Many important programs do not have a GUI, including most of the GNU userland. This comes from the Unix philosophy of designing a program to do one thing, and to do it well. The CLI is particularly suited for automation of repetitive or delayed tasks, and there is a natural progression where the command to perform a task is first issued directly, and then later reused in a script to provide automation.

Graphical and command line interfaces can also complement each other. There are a host of graphical terminal emulator programs, including xterm, rxvt, aterm, gnome-terminal, and konsole. For these programs, the X11 copy and paste mechanism can facilitate communication between the terminal and GUI applications. Additionally, KDE provides dcop, an efficient mechanism for navigating and therefore automatic all graphical applications from the command line.

[edytuj] X window managers

Zobacz więcej w osobnym artykule: X window manager.

The traditional GUI for a Linux operating system is based on a stand-alone X window manager such as FVWM, Enlightenment, or Window Maker, and a suite of diverse applications running under it. The window manager provides a means to control the placement and appearance of individual application windows, and interacts with the X window system.

The inconvenience of using a stand-alone window manager is that it requires a significant effort to customize it for the individual preferences of the user. Additionally, there will be an inconsistency between the interfaces of individual applications; the screenshot shows XMMS, RealPlayer, Mozilla Firefox, xterm, gaim, and Konqueror, each with their own conventions as to appearance, behaviour, keyboard shortcuts, menu organization, and copy and paste mechanisms. While individual applications can have brilliant aspects, the ensemble can be confusing and awkward to use together, and reflexes learned in one application are essentially non-transferable skills.

On the other hand, the high degree of flexibility allows power users to adapt a window manager to their specific needs, and the resource requirements in terms of CPU, memory, and hard-disk space consumption are much lower than those of a full-fledged desktop environment. A heavy command line interface user might prefer a minimal working environment, and a window manager used by itself provides just enough control of terminal emulator windows.

[edytuj] Desktop environments

Zobacz więcej w osobnych artykułach: desktop environment, GNOME, KDE.

The use of window managers by themselves declined with the rise of Linux desktop environments. These are integrated desktop workstation solutions that aim to provide an interface comparable in usability to that of Mac OS X and Microsoft Windows. They combine a window manager with a suite of standard applications that adhere to human interface guidelines. Whereas a window manager is analagous to the Aqua user interface for OS X, a Linux desktop environment is analagous to Aqua as well as all of the default OS X graphical applications and configuration utilities. Initially, CDE was available as a proprietary solution, but was never popular on Linux systems due to cost and licensing restrictions.Szablon:Fact In 1996 the KDE was announced, followed in 1997 by the announcement of GNOME. Xfce is a smaller project that was also founded in 1997, and focuses on speed and modularity. A comparison of X Window System desktop environments demonstrates the differences between environments. Today, GNOME and KDE are the dominant solutions, and often installed by default on Linux systems. Each of them offers:

• To programmers, a set of standard APIs, a programming environment, and human interface guidelines.
• To translators, a collaboration infrastructure. KDE and GNOME are available in many languages.^[38][39]
• To artists, a workspace to share their talents.^[40][41]
• To ergonomics specialists, the chance to help simplify the working environment.^[42][43][44]
• To developers of third-party applications, a reference environment for integration. OpenOffice.org is one such application.^[45][46]
• To users, a complete desktop environment and a suite of essential applications. These include a file manager, web browser, multimedia player, email client, address book, PDF reader, photo manager, and system preferences application.

In the early 2000's these two environments reached maturity.^[47]Szablon:Fact Still active, the Appeal^[48] and ToPaZ^[49] projects focus on bringing new advances to the next major releases of both KDE and GNOME respectively. Although striving for broadly similar goals, GNOME and KDE do differ in their approach to user ergonomics. KDE encourages applications to integrate and interoperate, is highly customizable, and contains many complex features, all whilst trying to establish sensible defaults. GNOME on the other hand is more prescriptive, and focuses on the finer details of essential tasks and overall simplification. Accordingly, each one attracts a different user and developer community. Technically, there are numerous technologies common to all Linux desktop environments, most obviously the X Window System. Accordingly, the freedesktop.org project was established as an informal collaboration zone with the goal being to reduce duplication of effort.

[edytuj] Applications

[edytuj] Desktop

Under Linux, desktop software in high demand is of high quality; this includes applications such as word processors, spreadsheets, email clients, and web browsers. The following are the major Linux desktop applications:

• Office: OpenOffice.org. It may be useful to compare office suites.
• Internet: Firefox, Thunderbird, Evolution, Gaim, and Azureus
• Multimedia: VLC, MPlayer, Xine, XMMS, and Amarok
• Graphics: The GIMP, Inkscape, and Scribus

Although in specialized application domains such as desktop publishing and professional audio there may be a lack of commercial quality software, users migrating from Mac OS X and Windows can find equivalent applications for most tasks.^[50] Furthermore, it is uncommon for a free software project that works under Windows or OS X not to have a Linux version; a user accustomed to using free software under Windows can generally expect to find the same applications running under Linux. A growing amount of proprietary desktop software is also supported under Linux,^[51] examples being Macromedia Flash, Adobe Acrobat, Opera, Skype, and Nero Burning ROM. Additionally, Crossover Office is a commercial solution based on the open source WINE project that supports running Windows versions of Microsoft Office and Photoshop.

[edytuj] Gaming

There are fewer games available for Linux than for Windows or console systems or Mac OS X; game development companies are generally reluctant to support an operating system with a small desktop market share. The games that are available can be classified into four categories: 1) open source games; 2) open source remakes or re-releases of classic games; 3) ports of proprietary games; 4) proprietary games that run under an emulator. The Linux Gamers' Game List is a long but selective list,^[52] and The Linux Game Tome is a database with many entries that is less discriminating but has user comments and rankings.^[53] There is also a list of Linux games, a list of commercial Linux games, and a list of professionally-developed Linux games.

There are few original open source games that have obtained notability. Battle for Wesnoth is a turn-based strategy game; Nethack and ZAngband are text-based computer role-playing games; Nexuiz is a first-person shooter; Tuxracer is a 3D racing game featuring Tux; and Vega Strike is a space flight simulation game. There are a larger number of open source remakes of classic games; one of the most publicized is FreeCiv, a remake of Civilization II. There is also OpenTTD, a remake of Transport Tycoon Deluxe; Frozen Bubble and Snood, adaptations of Puzzle Bobble; Scorched 3D, a 3D adaptation of Scorched Earth; Ur-Quan Masters, based on the original source code for Star Control II; Homeworld SDL, based on the original source code for Homeworld; StepMania, a remake of Dance Dance Revolution; Crack Attack!, inspired by Tetris Attack; various remakes of Doom, Wolfenstein 3D, and Quake based on the engines for these games; and two different remakes of Wing Commander: Privateer based on the Vega Strike engine.

In some cases, developers have released Linux ports of their games directly. iD Software together with Raven Software ported Doom 3, the Quake series, and Return to Castle Wolfenstein; Bioware released Neverwinter Nights; Epic Games released Unreal Tournament 2003 and Unreal Tournament 2004; Croatem released the Serious Sam series; and Introversion released Darwinia and Uplink. More commonly, an independent company has taken on the task of porting prominent Windows games to Linux. Loki Software was the first such company, and between 1998 and 2002 ported Descent³, Heretic II, Heroes of Might and Magic III, Myth II: Soulblighter, Railroad Tycoon II, Rune, Sid Meier's Alpha Centauri, Sim City 3000, Tribes II, and Unreal Tournament. Linux Game Publishing was founded in 2001 in response to the impending demise of Loki, and has brought Cold War, Postal 2, and X2: The Threat to Linux. Finally, icculus.org has ported Aliens versus Predator, Duke Nukem 3D, Medal of Honor: Allied Assault, and Rise of the Triad.

There are also API's, virtual machines, and machine emulators that provide binary compatability: WINE and the commercial Cedega fork exist for Windows games; Snes9x and ZSNES for the Super Nintendo; ePSXe and PCSX for the Playstation; Mupen64 for the Nintendo 64; VisualBoy Advance for the GameBoy Advance; ScummVM for LucasArts adventures; DOSBox for MS DOS; UAE for the Amiga; Frotz for Z-Machine text adventures; and finally Java and Flash for games targeting these platforms.

As far as development is concerned, library support for Linux gaming is provided directly by OpenGL and ALSA, or by SDL, a cross-platform multimedia wrapper around system-dependent libraries. The DRI project provides open source video card drivers, and NVidia, and ATI also release binary kernel modules for their video cards. Linux also runs on several game consoles, including the Xbox,^[54], Playstation 2, and Gamecube,^[55] which allows game developers without an expensive game development kit to access console hardware.

[edytuj] Servers, supercomputers and embedded devices

Historically, Linux has mainly been used as a server operating system, and has risen to prominence in that area; Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies run Linux on their web servers.^[56] This is due to its relative stability and long uptimes, and the fact that desktop software with a graphical user interface is often unneeded. Enterprise and non-enterprise Linux distributions may be found running on servers. Linux is the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.

Linux is commonly used as an operating system for supercomputers. As of January 5 2007, out of the top 500 systems, 376 (75.2%) run Linux.^[57]

Due to its low cost and its high configurability, an embedded Linux is often used in embedded systems such as television set-top boxes, mobile phones, and handheld devices. Linux has become a major competitor to the proprietary Symbian OS found in many mobile phones (16.7% of smartphones sold worldwide during 3Q, 2006 were using Linux^[58]), and it is an alternative to the dominant Windows CE and Palm OS operating systems on handheld devices. The popular TiVo digital video recorder uses a customized version of Linux.^[59] Several network firewall and router standalone products, including several from Linksys, use Linux internally, using its advanced firewalling and routing capabilities.

[edytuj] Software development

Most Linux distributions support dozens of programming languages. Core system software such as libraries and basic utilities are usually written in C. Enterprise software is often written in C, C++, Java, Perl, Ruby, or Python. The most common collection of utilities for building both Linux applications and operating system programs is found within the GNU toolchain, which includes the GNU Compiler Collection (GCC) and the GNU build system. Amongst others, GCC provides compilers for C, C++, Java, and Fortran. The Linux kernel itself is written to be compiled with GCC.

Most distributions also include support for Perl, Ruby, Python and other dynamic languages. Examples of languages that are less common, but still well-supported, are C# via the Mono project, and Scheme. A number of Java Virtual Machines and development kits run on Linux, including the original Sun Microsystems JVM (HotSpot), and IBM's J2SE RE, as well as many open-source projects like Kaffe. The two main frameworks for developing graphical applications are those of GNOME and KDE. These projects are based on the GTK+ and Qt widget toolkits, respectively, which can also be used independently of the larger framework. Both support a wide variety of languages. There are a number of Integrated development environments available including MonoDevelop, KDevelop, Anjuta, NetBeans, and Eclipse while the traditional editors Vim and Emacs remain popular.^[60]

As well as these free and open source options, there are proprietary compilers and tools available from a range of companies such as the Intel C++ Compiler, PathScale,^[61] Micro Focus COBOL,^[62] Franz Inc,^[63] and the Portland Group.^[64]

[edytuj] Comparisons with other operating systems

[edytuj] Comparison of Windows and Linux

Zobacz więcej w osobnym artykule: Comparison of Windows and Linux.

Due to the prevalence of Windows from the mid-1990s onwards, a comparison between Windows and Linux became a common topic of conversation among computer enthusiasts. In the past, Linux and other free software projects have been frequently criticized for not going far enough to ensure ease of use.^[65] However, the Berlin-based user experience organization Relevantive concluded in 2003 that the usability of Linux for a set of desktop-related tasks was "nearly equal to Windows XP."^[66] Since then, there have been numerous independent studies and articles which indicate that a modern Linux desktop using either GNOME or KDE is on par with Microsoft Windows, even in a business setting.^[67]

Although lack of application support is often cited as a reason to use Windows over Linux, compatibility layers such as Wine or NdisWrapper allow some Microsoft Windows applications and drivers to be used on Linux without requiring the vendor to adapt them. This allows users to more easily migrate from Windows to Linux since they can still run many of their Windows applications with little additional effort. Additionally, commercial software such as CrossOver have been developed which extend Wine to allow many commercial Windows applications to run in a Linux environment. In a similar fashion, Cygwin and Microsoft Windows Services for UNIX make it possible for users of Windows to run some GNU and other software normally only available on Linux and other Unix-like systems.

[edytuj] References

• Szablon:Cite book
• Szablon:Cite book
• Szablon:Cite web
• Szablon:Cite web
• Szablon:Cite web

[edytuj] Notes

Szablon:Reflist

[edytuj] See also

Szablon:Portalpar

• List of Linux distributions
• Comparison of Linux distributions
• The Cathedral and the Bazaar
• Total cost of ownership
• DistroWatch
• Linux software
• List of Linux games
• List of commercial Linux games
• List of professionally-developed Linux games

[edytuj] External links

Szablon:Sisterlinks

• Linux Wiki.
• Kernel.org — Linux kernel web site
• The Linux Documentation Project — HOWTOs, FAQs and other guides.
• Linux.org — contains comprehensive information and resources about Linux.
• GNU.org — The GNU Project web site
• FSF.org — The Free Software Foundation web site
• LinuxLinks.com - The Linux Portal site
• Two major Linux groups to merge Jan, 2007
• The Linux Documentation Project — A source of so many Linux related documentation
• Comprehensive Linux Textbook — A free Linux Book.

Szablon:Unix-like Szablon:Linux-distro

pl:Linux