Open-source software is a type of computer software in which source code is released under a license in which the copyright holder grants users the rights to study and distribute the software to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration. Open-source software development generates an more diverse scope of design perspective than any company is capable of developing and sustaining long term. A 2008 report by the Standish Group stated that adoption of open-source software models have resulted in savings of about $60 billion per year for consumers. In the early days of computing and developers shared software in order to learn from each other and evolve the field of computing; the open-source notion moved to the way side of commercialization of software in the years 1970-1980. However, academics still developed software collaboratively. For example Donald Knuth in 1979 with the TeX typesetting system or Richard Stallman in 1983 with the GNU operating system.
In 1997, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the hacker community and free-software principles. The paper received significant attention in early 1998, was one factor in motivating Netscape Communications Corporation to release their popular Netscape Communicator Internet suite as free software; this source code subsequently became the basis behind SeaMonkey, Mozilla Firefox and KompoZer. Netscape's act prompted Raymond and others to look into how to bring the Free Software Foundation's free software ideas and perceived benefits to the commercial software industry, they concluded that FSF's social activism was not appealing to companies like Netscape, looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The new term they chose was "open source", soon adopted by Bruce Perens, publisher Tim O'Reilly, Linus Torvalds, others; the Open Source Initiative was founded in February 1998 to encourage use of the new term and evangelize open-source principles.
While the Open Source Initiative sought to encourage the use of the new term and evangelize the principles it adhered to, commercial software vendors found themselves threatened by the concept of distributed software and universal access to an application's source code. A Microsoft executive publicly stated in 2001 that "open source is an intellectual property destroyer. I can't imagine something that could be worse than this for the software business and the intellectual-property business." However, while Free and open-source software has played a role outside of the mainstream of private software development, companies as large as Microsoft have begun to develop official open-source presences on the Internet. IBM, Oracle and State Farm are just a few of the companies with a serious public stake in today's competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS; the free-software movement was launched in 1983. In 1998, a group of individuals advocated that the term free software should be replaced by open-source software as an expression, less ambiguous and more comfortable for the corporate world.
Software licenses grant rights to users which would otherwise be reserved by copyright law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition; the most prominent and popular example is the GNU General Public License, which "allows free distribution under the condition that further developments and applications are put under the same licence", thus free. The open source label came out of a strategy session held on April 7, 1998 in Palo Alto in reaction to Netscape's January 1998 announcement of a source code release for Navigator. A group of individuals at the session included Tim O'Reilly, Linus Torvalds, Tom Paquin, Jamie Zawinski, Larry Wall, Brian Behlendorf, Sameer Parekh, Eric Allman, Greg Olson, Paul Vixie, John Ousterhout, Guido van Rossum, Philip Zimmermann, John Gilmore and Eric S. Raymond, they used the opportunity before the release of Navigator's source code to clarify a potential confusion caused by the ambiguity of the word "free" in English.
Many people claimed that the birth of the Internet, since 1969, started the open-source movement, while others do not distinguish between open-source and free software movements. The Free Software Foun
Chrome OS is a Linux kernel-based operating system designed by Google. It is derived from the free software Chromium OS and uses the Google Chrome web browser as its principal user interface; as a result, Chrome OS supports web applications. Google announced the project in July 2009, conceiving it as an operating system in which both applications and user data reside in the cloud: hence Chrome OS runs web applications. Source code and a public demo came that November; the first Chrome OS laptop, known as a Chromebook, arrived in May 2011. Initial Chromebook shipments from Samsung and Acer occurred in July 2011. Chrome OS has file manager, it supports Chrome Apps, which resemble native applications, as well as remote access to the desktop. Android applications started to become available for the operating system in 2014, in 2016, access to Android apps in the entire Google Play Store was introduced on supported Chrome OS devices. Reception was skeptical, with some observers arguing that a browser running on any operating system was functionally equivalent.
As more Chrome OS machines have entered the market, the operating system is now evaluated apart from the hardware that runs it. Chrome OS is only available pre-installed on hardware from Google manufacturing partners, but there are unofficial methods that allow it to be installed in other equipment. An open source equivalent, Chromium OS, can be compiled from downloaded source code. Early on, Google provided design goals for Chrome OS, but has not otherwise released a technical description. Google announced Chrome OS on July 7, 2009, describing it as an operating system in which both applications and user data reside in the cloud. To ascertain marketing requirements, the company relied on informal metrics, including monitoring the usage patterns of some 200 Chrome OS machines used by Google employees. Developers noted their own usage patterns. Matthew Papakipos, former engineering director for the Chrome OS project, put three machines in his house and found himself logging in for brief sessions: to make a single search query or send a short email.
Chrome OS was intended for secondary devices like netbooks, not as a user's primary PC. While Chrome OS supports hard disk drives, Google has requested that its hardware partners use solid-state drives "for performance and reliability reasons" as well as the lower capacity requirements inherent in an operating system that accesses applications and most user data on remote servers. In November 2009 Matthew Papakipos, engineering director for the Chrome OS, claimed that the Chrome OS consumes one-sixtieth as much drive space as Windows 7; the recovery images Google provides for Chrome OS range between 1 and 3 GB. On November 19, 2009, Google released Chrome OS's source code as the Chromium OS project. At a November 19, 2009, news conference, Sundar Pichai, at the time Google's vice president overseeing Chrome, demonstrated an early version of the operating system, he previewed a desktop which looked similar to the Chrome browser, in addition to the regular browser tabs had application tabs, which take less space and can be pinned for easier access.
At the conference, the operating system booted up in seven seconds, a time Google said it would work to reduce. Additionally, Chris Kenyon, vice president of OEM services at Canonical Ltd, announced that Canonical was under contract to contribute engineering resources to the project with the intent to build on existing open source components and tools where feasible. In 2010, Google released the unbranded Cr-48 Chromebook in a pilot program; the launch date for retail hardware featuring Chrome OS was delayed from late 2010 until the next year. On 11 May 2011, Google announced two Chromebooks from Acer and Samsung at Google I/O; the Samsung model was released on 15 June 2011. In August 2011, Netflix announced official support for Chrome OS through its streaming service, allowing Chromebooks to watch streaming movies and TV shows via Netflix. At the time, other devices had to use Microsoft Silverlight to play videos from Netflix. In that same month, Citrix released a client application for Chrome OS, allowing Chromebooks to access Windows applications and desktops remotely.
Dublin City University became the first educational institution in Europe to provide Chromebooks for its students when it announced an agreement with Google in September 2011. By 2012, demand for Chromebooks had begun to grow, Google announced a new range of devices and manufactured by Samsung. In so doing, they released the first Chromebox, the Samsung Series 3, Chrome OS's entrance into the world of desktop computers. Although they were faster than the previous range of devices, they were still underpowered compared to other desktops and laptops of the time, fitting in more with the Netbook market. Only months in October and Google released a new Chromebook at a lower price point, it was the first Chromebook to use one from Samsung's Exynos line. In order to reduce the price and Samsung reduced the memory and screen resolution of the device. An advantage of using the ARM processor, was that the Chromebook didn't require a fan. Acer followed after with the C7 Chromebook, priced lower, but containing an Intel Celeron processor.
One notable way which Samsung reduced the cost of the C7 was to use a laptop hard disk rather than a solid state drive. In April 2012, Google made the first update to Chrome OS's user interface since the operating system had launched, introducing a hardware-accelerated window manager called "Aura" along with a conventional taskbar
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct computers and makes them appear to be a single computer; the development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine; when computers in a group work in cooperation, they form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. Embedded operating systems are designed to be used in embedded computer systems, they are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources, they are compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri
The GNU Manifesto was written by Richard Stallman and published in March 1985 in Dr. Dobb's Journal of Software Tools as an explanation of goals of the GNU Project, as a call for support and participation in developing GNU, a free software computer operating system, it is held in high regard within the free software movement as a fundamental philosophical source. The full text is included with GNU software such as Emacs, is publicly available; some parts of the GNU Manifesto begun as an announcement of the GNU Project posted by Richard Stallman on September 27, 1983 in form of email on Usenet newsgroups. The project's aim was to give computer users freedom and control over their computers by collaboratively developing and providing software, based on Stallman's idea of software freedom; the manifesto was written as a way to familiarize more people with these concepts, to find more support in form of work, money and hardware. The GNU Manifesto has taken its name and full form in 1985 and was updated in minor ways in 1987.
The GNU Manifesto opens with an explanation of what the GNU Project is, what is the current, at the time, progress in creation of the GNU operating system. The system, although based on, compatible with Unix, is meant by the author to have many improvements over it, which are listed in detail in the manifesto. One of the major driving points behind the GNU project, according to Stallman, is the rapid trend toward Unix and its various components becoming proprietary software; the manifesto lays a philosophical basis for launching the project, importance of bringing it to fruition — proprietary software is a way to divide users, who are no longer able to help each other. Stallman refuses to write proprietary software as a sign of solidarity with them; the author provides many reasons for why the project and software freedom is beneficial to users, although he agrees that its wide adoption will make a work of programmer less profitable. Large part of the GNU Manifesto is focused on rebutting possible objections to GNU Project's goals.
They include the programmer's need to make a living, the issue of advertising ad distributing free software, the perceived need of a profit incentive. History of free and open-source software Open Letter to Hobbyists GNU Manifesto
Android (operating system)
Android is a mobile operating system developed by Google. It is based on a modified version of the Linux kernel and other open source software, is designed for touchscreen mobile devices such as smartphones and tablets. In addition, Google has further developed Android TV for televisions, Android Auto for cars, Wear OS for wrist watches, each with a specialized user interface. Variants of Android are used on game consoles, digital cameras, PCs and other electronics. Developed by Android Inc. which Google bought in 2005, Android was unveiled in 2007, with the first commercial Android device launched in September 2008. The operating system has since gone through multiple major releases, with the current version being 9 "Pie", released in August 2018. Google released the first Android Q beta on all Pixel phones on March 13, 2019; the core Android source code is known as Android Open Source Project, is licensed under the Apache License. Android is associated with a suite of proprietary software developed by Google, called Google Mobile Services that frequently comes pre-installed in devices, which includes the Google Chrome web browser and Google Search and always includes core apps for services such as Gmail, as well as the application store and digital distribution platform Google Play, associated development platform.
These apps are licensed by manufacturers of Android devices certified under standards imposed by Google, but AOSP has been used as the basis of competing Android ecosystems, such as Amazon.com's Fire OS, which use their own equivalents to GMS. Android has been the best-selling OS worldwide on smartphones since 2011 and on tablets since 2013; as of May 2017, it has over two billion monthly active users, the largest installed base of any operating system, as of December 2018, the Google Play store features over 2.6 million apps. The name Andrew and the noun Android share the Greek root andros. Andy Rubin picked android.com as his personal website, his colleagues used Android as his nickname at work. That became the name of the company he founded, the name of the operating system they developed. Android Inc. was founded in Palo Alto, California, in October 2003 by Andy Rubin, Rich Miner, Nick Sears, Chris White. Rubin described the Android project as "tremendous potential in developing smarter mobile devices that are more aware of its owner's location and preferences".
The early intentions of the company were to develop an advanced operating system for digital cameras, this was the basis of its pitch to investors in April 2004. The company decided that the market for cameras was not large enough for its goals, by five months it had diverted its efforts and was pitching Android as a handset operating system that would rival Symbian and Microsoft Windows Mobile. Rubin had difficulty attracting investors early on, Android was facing eviction from its office space. Steve Perlman, a close friend of Rubin, brought him $10,000 in cash in an envelope, shortly thereafter wired an undisclosed amount as seed funding. Perlman refused a stake in the company, has stated "I did it because I believed in the thing, I wanted to help Andy."In July 2005, Google acquired Android Inc. for at least $50 million. Its key employees, including Rubin and White, joined Google as part of the acquisition. Not much was known about the secretive Android at the time, with the company having provided few details other than that it was making software for mobile phones.
At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel. Google marketed the platform to handset makers and carriers on the promise of providing a flexible, upgradeable system. Google had "lined up a series of hardware components and software partners and signaled to carriers that it was open to various degrees of cooperation". Speculation about Google's intention to enter the mobile communications market continued to build through December 2006. An early prototype had a close resemblance to a BlackBerry phone, with no touchscreen and a physical QWERTY keyboard, but the arrival of 2007's Apple iPhone meant that Android "had to go back to the drawing board". Google changed its Android specification documents to state that "Touchscreens will be supported", although "the Product was designed with the presence of discrete physical buttons as an assumption, therefore a touchscreen cannot replace physical buttons". By 2008, both Nokia and BlackBerry announced touch-based smartphones to rival the iPhone 3G, Android's focus switched to just touchscreens.
The first commercially available smartphone running Android was the HTC Dream known as T-Mobile G1, announced on September 23, 2008. On November 5, 2007, the Open Handset Alliance, a consortium of technology companies including Google, device manufacturers such as HTC, Motorola and Samsung, wireless carriers such as Sprint and T-Mobile, chipset makers such as Qualcomm and Texas Instruments, unveiled itself, with a goal to develop "the first open and comprehensive platform for mobile devices". Within a year, the Open Handset Alliance faced two other open source competitors, the Symbian Foundation and the LiMo Foundation, the latter developing a Linux-based mobile operating system like Google. In September 2007, InformationWeek covered an Evalueserve study reporting that Google had filed several patent applications in the area of mobile telephony. Since 2008, Android has seen numerous updates which have incrementally improved the operating system, adding new features and fixing bugs in previous releases.
Each major release is named in alphabetical order after a dessert or sugary treat, with the first few Android versions being called "Cupcake", "Donut"
NetBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution. It was the first open-source BSD descendant released after 386BSD was forked, it continues to be developed and is available for many platforms, including servers, handheld devices, embedded systems. The NetBSD project focuses on code clarity, careful design, portability across many computer architectures, its source code is permissively licensed. NetBSD was derived from the 4.3BSD-Reno release of the Berkeley Software Distribution from the Computer Systems Research Group of the University of California, via their Net/2 source code release and the 386BSD project. The NetBSD project began as a result of frustration within the 386BSD developer community with the pace and direction of the operating system's development; the four founders of the NetBSD project, Chris Demetriou, Theo de Raadt, Adam Glass, Charles Hannum, felt that a more open development model would benefit the project: one centered on portable, correct code.
They aimed to produce a multi-platform, production-quality, BSD-based operating system. The name "NetBSD" was suggested by De Raadt, based on the importance and growth of networks such as the Internet at that time, the distributed, collaborative nature of its development; the NetBSD source code repository was established on 21 March 1993 and the first official release, NetBSD 0.8, was made on 19 April 1993. This was derived from 386BSD 0.1 plus the version 0.2.2 unofficial patchkit, with several programs from the Net/2 release missing from 386BSD re-integrated, various other improvements. The first multi-platform release, NetBSD 1.0, was made in October 1994, being updated with 4.4BSD-Lite sources, it was free of all encumbered 4.3BSD Net/2 code. In 1994, for disputed reasons, one of the founders, Theo de Raadt, was removed from the project, he founded a new project, OpenBSD, from a forked version of NetBSD 1.0 near the end of 1995. In 1998, NetBSD 1.3 introduced the pkgsrc packages collection.
Until 2004, NetBSD 1.x releases were made at annual intervals, with minor "patch" releases in between. From release 2.0 onwards, NetBSD uses semantic versioning, each major NetBSD release corresponds to an incremented major version number, i.e. the major releases following 2.0 are 3.0, 4.0 and so on. The previous minor releases are now divided into two categories: x.y "stable" maintenance releases and x.y.z releases containing only security and critical fixes. As the project's motto suggests, NetBSD has been ported to a large number of 32- and 64-bit architectures; these range from VAX minicomputers to Pocket PC PDAs. As of 2009, NetBSD supports 57 hardware platforms; the kernel and userland for these platforms are all built from a central unified source-code tree managed by CVS. Unlike other kernels such as μClinux, the NetBSD kernel requires the presence of an MMU in any given target architecture. NetBSD's portability is aided by the use of hardware abstraction layer interfaces for low-level hardware access such as bus input/output or DMA.
Using this portability layer, device drivers can be split into "machine-independent" and "machine-dependent" components. This makes a single driver usable on several platforms by hiding hardware access details, reduces the work to port it to a new system; this permits a particular device driver for a PCI card to work without modifications, whether it is in a PCI slot on an IA-32, PowerPC, SPARC, or other architecture with a PCI bus. A single driver for a specific device can operate via several different buses, like ISA, PCI, or PC Card. In comparison, Linux device driver code must be reworked for each new architecture; as a consequence, in porting efforts by NetBSD and Linux developers, NetBSD has taken much less time to port to new hardware. This platform independence aids the development of embedded systems since NetBSD 1.6, when the entire toolchain of compilers, assemblers and other tools support cross-compiling. In 2005, as a demonstration of NetBSD's portability and suitability for embedded applications, Technologic Systems, a vendor of embedded systems hardware and demonstrated a NetBSD-powered kitchen toaster.
Commercial ports to embedded platforms, including the AMD Geode LX800, Freescale PowerQUICC processors, Marvell Orion, AMCC 405 family of PowerPC processors, Intel XScale IOP and IXP series, were available from and supported by Wasabi Systems. The NetBSD cross-compiling framework lets a developer build a complete NetBSD system for an architecture from a more powerful system of different architecture, including on a different operating system. Several embedded systems using NetBSD have required no additional software development other than toolchain and target rehost. NetBSD features pkgsrc, a framework for building and managing third-party application software packages; the pkgsrc collection consists of more than 18,000 packages as of April 2018. Building and installing packages such as KDE, GNOME, the Apache HTTP Server or Perl is performed through the use of a system of makefiles; this can automatically fetch the source code, patch, configure and install the package such that it can be removed again later.
An alternative to compiling from source is to use a precompiled binary package. In either case, any prerequisites/dependencies will be installed automatically by the package system, without need for manual intervention. Pkgsrc supports not only NetBSD, but several other BSD variants like
A command-line interface or command language interpreter known as command-line user interface, console user interface and character user interface, is a means of interacting with a computer program where the user issues commands to the program in the form of successive lines of text. A program which handles the interface is called shell; the CLI was the primary means of interaction with most computer systems on computer terminals in the mid-1960s, continued to be used throughout the 1970s and 1980s on OpenVMS, Unix systems and personal computer systems including MS-DOS, CP/M and Apple DOS. The interface is implemented with a command line shell, a program that accepts commands as text input and converts commands into appropriate operating system functions. Today, many end users if use command-line interfaces and instead rely upon graphical user interfaces and menu-driven interactions. However, many software developers, system administrators and advanced users still rely on command-line interfaces to perform tasks more efficiently, configure their machine, or access programs and program features that are not available through a graphical interface.
Alternatives to the command line include, but are not limited to text user interface menus, keyboard shortcuts, various other desktop metaphors centered on the pointer. Examples of this include the Windows versions 1, 2, 3, 3.1, 3.11, DosShell, Mouse Systems PowerPanel. Programs with command-line interfaces are easier to automate via scripting. Command-line interfaces for software other than operating systems include a number of programming languages such as Tcl/Tk, PHP, others, as well as utilities such as the compression utility WinZip, some FTP and SSH/Telnet clients. Compared with a graphical user interface, a command line requires fewer system resources to implement. Since options to commands are given in a few characters in each command line, an experienced user finds the options easier to access. Automation of repetitive tasks is simplified - most operating systems using a command line interface support some mechanism for storing used sequences in a disk file, for re-use. A command-line history can be kept, allowing repetition of commands.
A command-line system may require paper or online manuals for the user's reference, although a "help" option provides a concise review of the options of a command. The command-line environment may not provide the graphical enhancements such as different fonts or extended edit windows found in a GUI, it may be difficult for a new user to become familiar with all the commands and options available, compared with the drop-down menus of a graphical user interface, without repeated reference to manuals. Operating system command line interfaces are distinct programs supplied with the operating system. A program that implements such a text interface is called a command-line interpreter, command processor or shell. Examples of command-line interpreters include DEC's DIGITAL Command Language in OpenVMS and RSX-11, the various Unix shells, CP/M's CCP, DOS's COMMAND. COM, as well as the OS/2 and the Windows CMD. EXE programs, the latter groups being based on DEC's RSX-11 and RSTS CLIs. Under most operating systems, it is possible to replace the default shell program with alternatives.
Although the term'shell' is used to describe a command-line interpreter speaking a'shell' can be any program that constitutes the user-interface, including graphically oriented ones. For example, the default Windows GUI is a shell program named EXPLORER. EXE, as defined in the SHELL=EXPLORER. EXE line in the WIN. INI configuration file; these programs are shells, but not CLIs. Application programs may have command line interfaces. An application program may support none, any, or all of these three major types of command line interface mechanisms: Parameters: Most operating systems support a means to pass additional information to a program when it is launched; when a program is launched from an OS command line shell, additional text provided along with the program name is passed to the launched program. Interactive command line sessions: After launch, a program may provide an operator with an independent means to enter commands in the form of text. OS inter-process communication: Most operating systems support means of inter-process communication.
Command lines from client processes may be redirected to a CLI program by one of these methods. Some applications support only a CLI, presenting a CLI prompt to the user and acting upon command lines as they are entered. Other programs support both a CLI and a GUI. In some cases, a GUI is a wrapper around a separate CLI executable file. In other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs support different functionality. For example, all features of MATLAB, a numerical analysis computer program, are available via the CLI, whereas the MATLAB GUI exposes only a subset of features; the early Sierra games, such as the first three King's Quest games, used commands from an internal command line to move the character around in the graphic window. The command-line interface evolved from a form of dialog once conducted by humans over teleprinter machines, in which human operators remotely exchanged inf