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Linux je opći pojam koje je uglavnom vezan za Unix-olike računalne operativne sustave koji koriste Linux jezgru. Linux je jedan od najistaknutijih primjera slobodnog softwera i otvorenog koda. Sve leži na otovrenom kodu koji se može slobodno koristiti, modificirati i davati ga svakome.

Linux je pretežno poznat po upotrebi na serverima, no također ga se instalira na široku paletu računalnog hardwera. Od posebno složenih uređaja preko mobilnih telefona, pa sve do superkompjutora. Popularnost na stolnim računalima i prijenosnicima mu sve više raste zahvaljujući sve prilagođenijim distribucijama ovog operativnog sustava.

Ime "Linux" dolazi od Linux jezgre (kernela), originalno napisanog 1991 od Linus Torvaldsa. Sistemski alati i biblioteke uglavnom dolaze od GNU operativnog sistema, objavljenog 1983. od Richarda Stallmana. GNU-ov doprinos je baza za alternativno ime GNU/Linux

Povijest

Richard Stallman, lijevo, začetnik GNU projekta i Linus Torvalds, desno, kreator Linux jezgre

Unix operacijski sustav je zamišljen i proveden 1960-ih i prvi puta izdan u 1970. Njegova široka dostupnost i prenosivost omogućila mu je da bude rasprostranjen, kopiran i mijenjan u korist akademskim institucijama i poslovnim subjektima, te je svojim dizajnom utjecao na autore drugih sustava.

GNU projekt počinje 1984. od strane Richarda Stallmana, sa ciljem potpuno Unix-kompatibilnog operacijskog sustava sačinjenog usključivo od slobodnog softwarea. Iduće godine Stallman osniva Free Software Foundation i piše GNU General Public Licencu (GNU GPL) 1989. Ranih 1990-ih mnogo je programa potrebnih za operacijski sustav (kao što su biblioteke, kompajleri, tekstualni editori, Unix školjku (shell) i sustav prozora) bilo završeno, ali elementi "niskog nivoa" kao što su pokretački programi za uređaje (driveri), daemoni i jezgra (kernel) nisu bili dovršeni. Linus Torvalds je rekao, da ako će GNU jezgra biti dostupna na vrijeme (1991.), tada on neće razvijati svoju vlastitu.

MINIX

MINIX, Unix-oidni sustav namjenjen akademskoj zajednici, izdan od Andrew S. Tanenbauma 1987. Dok je izvorni kod sustava bio dostupan, modifikacije i daljnja distribucija bile su zabranjene (što danas više nije slučaj). Nadalje, MINIX-ov 16-bitni dizajn nije bio dobro prenesen u 32-bitni koncept jeftinog i popularnog PC-ja zasnovanog na Intel 386 arhitekturi.

U 1991. prilikom sudjelovanja na Sveučilištu u Helsinkiju, Torvalds je počeo raditi na ne-komercijalnoj zamjeni za MINIX koji bi eventualno mogao postati Linux jezgra. U 1992. Tanenbaum je postavio članak na Usenet tvrdeći da je Linux zastario. On je u članku kritizirao operativni sustav kao monolitni u dizajnu i kako je usko vezan na x86 arhitekturu, te time neprenosiv, te mu je to pripisao kao "temeljnu pogrešku." Tanenbaum je predložio da oni koji žele izgraditi moderan operativni sustav trebali bi ga zasnivati na temelju microkernel modela. Iz ovakvog načina razmišljanja razvila se poznata debata o microkernelskim i monolitnim oblikovanjima jezgara operativnih sustava.

U prvo vrijeme, Linux je bio ovisan o MINIX-ovim korisnicima. Činilo se da bi bilo korisno za izgradnju operativnog sustava upotrijebiti kod od GNU sustava koji je slobodno dostupan. Kod licenciran pod GNU GPL licencom može se koristiti u drugim projektima, tako dugo dok su i oni izdani pod istom ili kompatibilnom licencom. U cilju da napravi Linux jezgru kompatibilnu sa ostalim komponentama operativnog sustava iz GNU projekta, Torvalds prelazi sa svoje originalne licence (koja zabranjuje komercijalnu upotrebu) na GNU GPL licencu. Linux i GNU programeri integrirali su GNU komponente sa Linuxom i dobili potpuno funkcionalni i slobodni operativni sustav.

Komercijalno i opće prihvaćanje Linuxa

Danas se Linux koristi u brojne svrhe. Od posebno složenih uređaja do superkompjutora, te je osigurao svoje mjesto među serverskim instalacijama sa popularnim LAMP aplikacijskim paketom. Korištenje Linux-a na kućnim i poslovnim računalima je u stalnom porastu, te danas drži značajan udio na tržištu računala.

Linux je također postao popularan u novom segmentu notebook računala, na strojevima kao što su ASUS Eee PC i Acer Aspire One koji se prodaju sa predinstaliranim i prilagođenim Linux distribucijama.

Trenutni razvoj

Torvalds nastavlja usmjeravati razvoj kernela. Stallman vodi Free Software Foundation, što zauzvrat osigurava GNU komponente. Konačno, pojedinci i korporacije razvijaju vlastite ne-GNU komponente. Te komponente obuhvaćaju veliki dio cjeline, te mogu uključivati kernel module, korisničke aplikacije i biblioteke. Linux distributeri i zajednica sklapa i distribuira kernel, GNU i ne-GNU komponente, te dodatne programime za upravljanje paketima i izdaje Linux operativne sustave u obliku Linux distribucija.

Dizajn (oblikovanje)

Linux je modularan, Unixu sličan operativni sustav, koji potječe od osnovnih načela dizajna iz Unixa tijekom 1970-tih i 1980tih godina. Linux koristi monolitni Linux kernel, koji obrađuje procesne radnje, umrežavanje, upravljanje perifernim uređajima i datotečnim sustavima. Upravljački programi su integrirani izravno u kernel.

Većinu Linux-ovih funkcionalnosti višeg stupnja osiguravaju odvojeni projekti koji surađuju s kernelom. GNU korisnička okolina (koja nije dio samog kernela) je važan dio većine Linux-ovih sustava, pružajući shell i Unix alate koji vode brigu o mnogim osnovnim zadaćama operativnog sustava. Na vrhu ovih alata je grafičko korisničko sučelje pokretano od strane X Windows sistema.

Korisničko sučelje

Linuxom se može upravljati na jedan ili više načina. Putem tekstualno baziranog linijskog upravljačkog sučelja (CLI - command line interface), grafičkog korisničkog sučelja (GUI - graphical user interface) (uobičajenog za stolna računala) ili putem upravljanja od uređaja samih (uobičajeno za posebno složene uređaje)

Na stolnim računalima, KDE, Gnome i Xfce su najpopularnija korisnička sučelja, iako postoji i niz drugih korisničkih sučelja. Najčitanije korisničkih sučelja prikazivati na vrhu su X Window System (X), koji osigurava transparentnost mreže, omogućavajući grafički program na jednom stroju koji će biti prikazani i kontrolirana od druge.

Ostalo GUIs uključuje X Window menadžeri poput FVWM, prosvjetiteljstva i Window Maker. The window manager osigurava sredstva za kontrolu položaj i izgled pojedinačnih prozora aplikacije, i interakciju s X Window System.

Linux sustav obično pruža CLI nekih poredajte preko ljuske, koja je tradicionalni način interakcije s Unix sustava. Linux distribucija specijalizirana za poslužitelje svibanj koristiti CLI kao samo sučelje. A "bezglav sustav" vožnju bez čak monitor može biti kontroliran putem naredbenog retka koristeći protokol kao što je SSH i telnet.

Većina niske razine Linux komponenti, uključujući GNU Userland, koristiti isključivo CLI. U CLI je posebno prilagođen za automatizacija ponavljaju ili kasniti zadatke, i nudi vrlo jednostavno inter-proces komunikacije. A grafički program za oponašanje terminala često se koristi za pristup CLI od Linux desktop

Razvoj

Predložak:Main

Povijest Unix-oidnih operativnih sistema pokazuje Linuxove korijene. Imajte na umu da usprkos sličnim arhitekturama i konceptima koji se dijele kao dio POSIX standarda, Linux ne dijeli niti jedan ne-slobodni dio izvornog koda od originalnog UNIX-a ili MINIX-a.

The primary difference between Linux and many other popular contemporary operating systems is that the Linux kernel and other components are free and open source software. Linux is not the only such operating system, although it is the best-known and most widely used. Some free and open source software licences 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, the GNU GPL, is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU project.

As an operating system underdog competing with mainstream operating systems, Linux cannot rely on a monopoly advantage; in order for Linux to be convenient for users, Linux aims for interoperability with other operating systems and established computing standards. Linux systems adhere to POSIX,^[1] SUS,^[2] ISO and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.^[3]

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.

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 different software packages into a coherent whole.

Zajednica

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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 Red Hat does with Fedora.

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 IRC chatrooms or newsgroups. Online forums are another means for support, with notable examples being LinuxQuestions.org and the Gentoo forums. Linux distributions host mailing lists; commonly there will be a specific topic such as usage or development for a given list.

There are several technology websites with a Linux focus. Print magazines on Linux often include cover disks including software or even complete Linux distributions.^[4][5]

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 Dell, IBM, HP, Sun Microsystems, Novell, Nokia. There are several corporations which built their entire business around Linux, notably Red Hat.

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. One common business model of commercial suppliers is 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. Another business model is to give away the software in order to sell hardware.

Progrmiranje u Linuxu

Most Linux distributions support dozens of programming languages. 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 Ada, C, C++, Java, and Fortran. The Linux kernel itself is written to be compiled with GCC. Proprietary compilers for Linux include the Intel C++ Compiler and IBM XL C/C++ Compiler.

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, sponsored by Novell, 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 Anjuta, Code::Blocks, Eclipse, KDevelop, Lazarus, MonoDevelop, NetBeans, and Omnis Studio while the long-established editors Vim and Emacs remain popular.^[6]

Upotreba

As well as those designed for general purpose use on desktops and servers, 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.^[7]

Linux is a widely ported operating system. The Linux kernel runs on the most diverse range of computer architectures: in the hand-held ARM-based iPAQ and the mainframe IBM System z9, in devices ranging from mobile phones to supercomputers.^[8] 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 fork may run on systems without a memory management unit. The kernel also runs on architectures that were only ever intended to use a manufacturer-created operating system, such as Macintosh computers, PDAs, video game consoles, portable music players, and mobile phones.

Stolna računala

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Although there is a lack of Linux ports for some Mac OS X and Microsoft Windows programs in domains such as desktop publishing^[9] and professional audio,^[10][11][12] support for common applications roughly equivalent to those available for Mac and Windows is available for Linux.^[13]

Most Linux distributions provide a program for browsing a list of thousands of free software applications that have already been tested and configured for a specific distribution. These free programs can be downloaded and installed with one mouse click and a digital signature guarantees that no one has added a virus or a spyware to these programs.

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.

Many free software titles that are popular on Windows, such as Pidgin, Mozilla Firefox, Openoffice.org, and GIMP, are available for Linux. A growing amount of proprietary desktop software is also supported under Linux,^[14] see List of proprietary software for Linux. In the field of animation and visual effects, most high end software, such as AutoDesk Maya, Softimage XSI and Apple Shake, is available for Linux, Windows and/or Mac OS X. CrossOver is a proprietary solution based on the open source Wine project that supports running older Windows versions of Microsoft Office and Adobe Photoshop versions through CS2. Microsoft Office 2007 and Adobe Photoshop CS3 are known not to work.^[15][16]

Besides the free Windows compatibility layer Wine, most distributions offer Dual boot and X86 virtualization for running both Linux and Windows on the same computer. According to the Wine developers, "Wine is still under development, and it is not yet suitable for general use."^[17]

Linux's open nature allows distributed teams to localize Linux distributions for use in locales where localizing proprietary systems would not be cost-effective. For example the Sinhalese language version of the Knoppix distribution was available for a long time before Microsoft Windows XP was translated to Sinhalese. In this case the Lanka Linux User Group played a major part in developing the localized system by combining the knowledge of university professors, linguists, and local developers.

The performance of Linux on the desktop has been a controversial topic; for example, Con Kolivas accused the Linux community of favoring performance on servers. He quit Linux development because he was frustrated with this lack of focus on the desktop, and then gave a 'tell all' interview on the topic.^[18]

Predložak:See also

Serveri i superkompjutori

Servers designed for Linux

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 ran Linux on their web servers.^[19] (As of June 2008, linux represented five of ten, FreeBSD three of ten, and Microsoft two of ten.^[20]) This is due to its relative stability and long uptime, and the fact that desktop software with a graphical user interface for servers 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 August 2008, out of the top 500 systems, 423 (84.6%) run Linux.^[21]

Autorska prava

The Linux kernel and most GNU software are licensed under the GNU General Public License (GPL). The GPL requires that anyone who distributes the Linux kernel must make the source code (and any modifications) available to the recipient under the same terms. In 1997, Linus Torvalds stated, “Making Linux GPL'd was definitely the best thing I ever did.”^[22] Other key components of a Linux system may use other licenses; many libraries use the GNU Lesser General Public License (LGPL), a more permissive variant of the GPL, and the X Window System uses the MIT License.

Torvalds has publicly stated that he would not move the Linux kernel (currently licensed under GPL version 2) to version 3 of the GPL, released in mid-2007, specifically citing some provisions in the new license which prohibit the use of the software in digital rights management.^[23][24]

GNU/Linux

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The Free Software Foundation views Linux distributions which use GNU software as GNU variants and they ask that such operating systems be referred to as GNU/Linux or a Linux-based GNU system.^[25] However, the media and population at large refers to this family of operating systems simply as Linux, as do many large Linux distributions (e.g. Ubuntu and SuSE Linux). Some distributions use GNU/Linux (particularly notable is Debian GNU/Linux), but the term's use outside of the enthusiast community is limited. The naming issue remains a source of confusion to many newcomers, and the naming remains controversial.

Dijelovi teksta preuzeti sa Wikipedije - O Linuxu

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17. ↑ WineHQ - About Wine
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21. ↑ Operating system Family share for 11/2007 | TOP500 Supercomputing Sites
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25. ↑ Predložak:Cite web