Interoperability
Linux aims for interoperability with other operating systems such as (but not limited to) Microsoft Windows and Mac OS X, and by extension the software that runs on Linux aims for interoperability with other Linux and non-Linux software. As an operating system underdog competing with mainstream operating systems, Linux 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. Interoperability also provides users free choice of software and data formats whilst not restricting them as a result of that choice.
Linux systems adhere to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.
A priority is placed on open formats, public specifications for data that are freely available and free to implement, such that there can be multiple competing independent implementations to choose from, instead of only a single piece of software which can work with a specific format. These contrast with proprietary 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,[citation needed] 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.
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 proprietary formats and communication protocols. Prime examples of the first category draw from the instant messaging war, which is ruled by multiprotocol software such as Pidgin, 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. 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 European Copyright Directive and Digital Millennium Copyright Act.
Portability
Linux is a widely ported Operating System. While the Linux kernel was originally designed only for Intel 80386 microprocessors, it now runs on a more diverse range of computer architectures than any other operating system from the hand-held ARM-based iPAQ to the mainframe IBM System z9, in devices ranging from supercomputers to mobile phones. 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, Nintendo DS and even the Playstation Portable.
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.
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. 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. The Linux Kernel Mailing List is a high-volume list where all Linux kernel development happens. SourceForge, Savannah, and Apache host many free and open source software projects using standard collaborative software.
Linux-based newsgroups are available via the Google Groups interface and also via news readers. There are also several technology websites with a Linux focus. Linux Weekly News is a weekly digest of Linux-related news; the Linux Journal is an online magazine of Linux articles published monthly; Slashdot is a technology-related news website with many stories on Linux and open source software; Groklaw has written in depth about Linux-related legal proceedings; and there are many articles relevant to Linux on the Free Software Foundation website.
People who contribute to free software are not all 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.
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, and 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.
The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach several hundred million schoolchildren and their families and communities in developing countries. Six countries have ordered a million or more units each for delivery in 2007 to distribute to schoolchildren at no charge. Google, Red Hat, and eBay are major supporters of the project.
Linux aims for interoperability with other operating systems such as (but not limited to) Microsoft Windows and Mac OS X, and by extension the software that runs on Linux aims for interoperability with other Linux and non-Linux software. As an operating system underdog competing with mainstream operating systems, Linux 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. Interoperability also provides users free choice of software and data formats whilst not restricting them as a result of that choice.
Linux systems adhere to POSIX, SUS, ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.
A priority is placed on open formats, public specifications for data that are freely available and free to implement, such that there can be multiple competing independent implementations to choose from, instead of only a single piece of software which can work with a specific format. These contrast with proprietary 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,[citation needed] 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.
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 proprietary formats and communication protocols. Prime examples of the first category draw from the instant messaging war, which is ruled by multiprotocol software such as Pidgin, 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. 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 European Copyright Directive and Digital Millennium Copyright Act.
Portability
Linux is a widely ported Operating System. While the Linux kernel was originally designed only for Intel 80386 microprocessors, it now runs on a more diverse range of computer architectures than any other operating system from the hand-held ARM-based iPAQ to the mainframe IBM System z9, in devices ranging from supercomputers to mobile phones. 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, Nintendo DS and even the Playstation Portable.
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.
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. 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. The Linux Kernel Mailing List is a high-volume list where all Linux kernel development happens. SourceForge, Savannah, and Apache host many free and open source software projects using standard collaborative software.
Linux-based newsgroups are available via the Google Groups interface and also via news readers. There are also several technology websites with a Linux focus. Linux Weekly News is a weekly digest of Linux-related news; the Linux Journal is an online magazine of Linux articles published monthly; Slashdot is a technology-related news website with many stories on Linux and open source software; Groklaw has written in depth about Linux-related legal proceedings; and there are many articles relevant to Linux on the Free Software Foundation website.
People who contribute to free software are not all 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.
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, and 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.
The XO laptop project of One Laptop Per Child is creating a new and potentially much larger Linux community, planned to reach several hundred million schoolchildren and their families and communities in developing countries. Six countries have ordered a million or more units each for delivery in 2007 to distribute to schoolchildren at no charge. Google, Red Hat, and eBay are major supporters of the project.
