1.
Linux
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Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds, the Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy. Linux was originally developed for computers based on the Intel x86 architecture. Because of the dominance of Android on smartphones, Linux has the largest installed base of all operating systems. Linux is also the operating system on servers and other big iron systems such as mainframe computers. It is used by around 2. 3% of desktop computers, the Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, many smartphones and tablet computers run Android and other Linux derivatives. The development of Linux is one of the most prominent examples of free, the underlying source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License. Typically, Linux is packaged in a known as a Linux distribution for both desktop and server use. Distributions intended to run on servers may omit all graphical environments from the standard install, because Linux is freely redistributable, anyone may create a distribution for any intended use. The Unix operating system was conceived and implemented in 1969 at AT&Ts Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, first released in 1971, Unix was written entirely in assembly language, as was common practice at the time. Later, in a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie, the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, as a result, Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs, freed of the legal obligation requiring free licensing, the GNU Project, started in 1983 by Richard Stallman, has the goal of creating a complete Unix-compatible software system composed entirely of free software. Later, in 1985, Stallman started the Free Software Foundation, by the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, although not released until 1992 due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has also stated that if 386BSD had been available at the time, although the complete source code of MINIX was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000
2.
AT&T
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AT&T Inc. is an American multinational telecommunications conglomerate, headquartered at Whitacre Tower in downtown Dallas, Texas. AT&T is the third-largest company in Texas, as of February 2017, AT&T is the 12th largest company in the world as measured by a composite of revenues, profits, assets and market valuation. AT&T is the largest telecommunications company in the world by revenue, as of 2017, it is also the 18th-largest mobile telecom operator in the world, with 135 million mobile customers. AT&T was ranked at #4 on the 2017 rankings of the worlds most valuable brands published by Brand Finance, Southwestern Bell changed its name to SBC Communications Inc. in 1995. In 2005, SBC purchased former parent AT&T Corp. and took on its branding, with the merged entity naming itself AT&T Inc. and using the iconic AT&T Corp. logo and stock-trading symbol. The current AT&T reconstitutes much of the former Bell System and includes ten of the original 22 Bell Operating Companies, AT&T can trace its origin back to the original Bell Telephone Company founded by Alexander Graham Bell after his invention of the telephone. This monopoly was known as the Bell System, and during this period, for periods of time, the former AT&T was the worlds largest phone company. In 1982, U. S. regulators broke up the AT&T monopoly, requiring AT&T to divest its regional subsidiaries and these new companies were known as Regional Bell Operating Companies, or more informally, Baby Bells. AT&T continued to long distance services, but as a result of this breakup, faced competition from new competitors such as MCI. Southwestern Bell was one of the created by the breakup of AT&T. The architect of divestiture for Southwestern Bell was Robert G. Pope, the company soon started a series of acquisitions. This includes the 1987 acquisition of Metromedia mobile business, and the acquisition of several companies in the early 1990s. In the later half of the 1990s, the company acquired several other companies, including some Baby Bells. During this time, the changed its name to SBC Communications. By 1998, the company was in the top 15 of the Fortune 500, in 2005, SBC purchased AT&T for $16 billion. After this purchase, SBC adopted the better-known AT&T name and brand, the current AT&T claims the original AT&Ts history as its own, though its corporate structure only dates from 1983. It also retains SBCs pre-2005 stock price history, in September 2013, AT&T announced it would expand into Latin America through a collaboration with Carlos Slims América Móvil. In December 2013, AT&T announced plans to sell its Connecticut wireline operations to Stamford-based Frontier Communications, in July 2015, AT&T purchased DirecTV for $48.5 billion, or $67.1 billion including assumed debt
3.
Unix
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Among these is Apples macOS, which is the Unix version with the largest installed base as of 2014. Many Unix-like operating systems have arisen over the years, of which Linux is the most popular, Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmer users. The system grew larger as the system started spreading in academic circles, as users added their own tools to the system. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration and these concepts are collectively known as the Unix philosophy. By the early 1980s users began seeing Unix as a universal operating system. Under Unix, the system consists of many utilities along with the master control program. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space, the microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. In an era when a standard computer consisted of a disk for storage and a data terminal for input and output. However, modern systems include networking and other new devices, as graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, and semaphores. In microkernel implementations, functions such as network protocols could be moved out of the kernel, Multics introduced many innovations, but had many problems. Frustrated by the size and complexity of Multics but not by the aims and their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna, decided to redo the work on a much smaller scale. The name Unics, a pun on Multics, was suggested for the project in 1970. Peter H. Salus credits Peter Neumann with the pun, while Brian Kernighan claims the coining for himself, in 1972, Unix was rewritten in the C programming language. Bell Labs produced several versions of Unix that are referred to as Research Unix. In 1975, the first source license for UNIX was sold to faculty at the University of Illinois Department of Computer Science, UIUC graduate student Greg Chesson was instrumental in negotiating the terms of this license. During the late 1970s and early 1980s, the influence of Unix in academic circles led to adoption of Unix by commercial startups, including Sequent, HP-UX, Solaris, AIX. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4, in the 1990s, Unix-like systems grew in popularity as Linux and BSD distributions were developed through collaboration by a worldwide network of programmers
4.
Microsoft
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Its best known software products are the Microsoft Windows line of operating systems, Microsoft Office office suite, and Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface tablet lineup, as of 2016, it was the worlds largest software maker by revenue, and one of the worlds most valuable companies. Microsoft was founded by Paul Allen and Bill Gates on April 4,1975, to develop and it rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows. The companys 1986 initial public offering, and subsequent rise in its share price, since the 1990s, it has increasingly diversified from the operating system market and has made a number of corporate acquisitions. In May 2011, Microsoft acquired Skype Technologies for $8.5 billion, in June 2012, Microsoft entered the personal computer production market for the first time, with the launch of the Microsoft Surface, a line of tablet computers. The word Microsoft is a portmanteau of microcomputer and software, Paul Allen and Bill Gates, childhood friends with a passion for computer programming, sought to make a successful business utilizing their shared skills. In 1972 they founded their first company, named Traf-O-Data, which offered a computer that tracked and analyzed automobile traffic data. Allen went on to pursue a degree in science at Washington State University. The January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systemss Altair 8800 microcomputer, Allen suggested that they could program a BASIC interpreter for the device, after a call from Gates claiming to have a working interpreter, MITS requested a demonstration. Since they didnt actually have one, Allen worked on a simulator for the Altair while Gates developed the interpreter and they officially established Microsoft on April 4,1975, with Gates as the CEO. Allen came up with the name of Micro-Soft, as recounted in a 1995 Fortune magazine article. In August 1977 the company formed an agreement with ASCII Magazine in Japan, resulting in its first international office, the company moved to a new home in Bellevue, Washington in January 1979. Microsoft entered the OS business in 1980 with its own version of Unix, however, it was MS-DOS that solidified the companys dominance. For this deal, Microsoft purchased a CP/M clone called 86-DOS from Seattle Computer Products, branding it as MS-DOS, following the release of the IBM PC in August 1981, Microsoft retained ownership of MS-DOS. Since IBM copyrighted the IBM PC BIOS, other companies had to engineer it in order for non-IBM hardware to run as IBM PC compatibles. Due to various factors, such as MS-DOSs available software selection, the company expanded into new markets with the release of the Microsoft Mouse in 1983, as well as with a publishing division named Microsoft Press. Paul Allen resigned from Microsoft in 1983 after developing Hodgkins disease, while jointly developing a new OS with IBM in 1984, OS/2, Microsoft released Microsoft Windows, a graphical extension for MS-DOS, on November 20,1985. Once Microsoft informed IBM of NT, the OS/2 partnership deteriorated, in 1990, Microsoft introduced its office suite, Microsoft Office
5.
IBM AIX
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AIX is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. AIX is based on UNIX System V with 4. 3BSD-compatible extensions and it is one of five commercial operating systems that have versions certified to The Open Groups UNIX03 standard. The AIX family of operating systems debuted in 1986, became the operating system for the RS/6000 series on its launch in 1990. It is currently supported on IBM Power Systems alongside IBM i, Unix started life at AT&Ts Bell Labs research center in the early 1970s, running on DEC minicomputers. By 1976, the system was in use at various academic institutions, including Princeton. This port would later grow out to become UTS, a mainframe Unix offering by IBMs competitor Amdahl Corporation, IBMs own involvement in Unix can be dated to 1979, when it assisted Bell Labs in doing its own Unix port to the 370. In the process, IBM made modifications to the TSS/370 hypervisor to better support Unix and it took until 1985 for IBM to offer its own Unix on the S/370 platform, IX/370, which was developed by Interactive Systems Corporation and intended by IBM to compete with Amdahl UTS. AIX Version 1, introduced in 1986 for the IBM6150 RT workstation, was based on UNIX System V Releases 1 and 2, in developing AIX, IBM and Interactive Systems Corporation also incorporated source code from 4.2 and 4.3 BSD UNIX. Among other variants, IBM later produced AIX Version 3, based on System V Release 3, since 1990, AIX has served as the primary operating system for the RS/6000 series. AIX Version 4, introduced in 1994, added symmetric multiprocessing with the introduction of the first RS/6000 SMP servers and continued to evolve through the 1990s, culminating with AIX4.3.3 in 1999. Version 4.1, in a modified form, was also the standard operating system for the Apple Network Server systems sold by Apple Computer to complement the Macintosh line. IBM maintains that their license was irrevocable, and continued to sell, AIX was a component of the 2003 SCO v. IBM lawsuit, in which the SCO Group filed a lawsuit against IBM, alleging IBM contributed SCOs intellectual property to the Linux codebase. The SCO Group, who argued they were the owners of the copyrights covering the Unix operating system. In March 2010, a jury returned a finding that Novell, not the SCO Group. AIX6 was announced in May 2007, and it ran as an open beta from June 2007 until the availability of AIX6.1 on November 9,2007. Major new features in AIX6.1 included full role-based access control, workload partitions, enhanced security, AIX7.1 was announced in April 2010, and an open beta ran until general availability of AIX7.1 in September 2010. Several new features, including better scalability, enhanced clustering and management capabilities were added, AIX7.1 includes a new built-in clustering capability called Cluster Aware AIX. AIX is able to organize multiple LPARs through the communications channel to neighboring CPUs
6.
Amazon (company)
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Amazon. com, also called Amazon, is an American electronic commerce and cloud computing company that was founded on July 5,1994, by Jeff Bezos and is based in Seattle, Washington. It is the largest Internet-based retailer in the world by total sales, the company also produces consumer electronics—notably, Kindle e-readers, Fire tablets, Fire TV, and Echo—and is the worlds largest provider of cloud infrastructure services. Amazon also sells certain low-end products like USB cables under its in-house brand AmazonBasics. Amazon has separate retail websites for the United States, the United Kingdom, Ireland, France, Canada, Germany, Italy, Spain, Netherlands, Australia, Brazil, Japan, China, India, and Mexico. Amazon also offers international shipping to other countries for some of its products. In 2016, Dutch, Polish, and Turkish language versions of the German Amazon website were launched. In 2015, Amazon surpassed Walmart as the most valuable retailer in the United States by market capitalization, in 1994, Bezos left his employment as vice-president of D. E. Shaw & Co. a Wall Street firm and moved to Seattle. He began to work on a plan for what would eventually become Amazon. com. Bezos incorporated the company as Cadabra on July 5,1994, Bezos changed the name to Amazon a year later after a lawyer misheard its original name as cadaver. In September 1994, Bezos purchased the URL Relentless. com and briefly considered naming his online store Relentless, the domain is still owned by Bezos and still redirects to the retailer. The company went online as Amazon. com in 1995, Bezos placed a premium on his head start in building a brand, telling a reporter, Theres nothing about our model that cant be copied over time. But you know, McDonalds got copied, and it still built a huge, multibillion-dollar company. A lot of it comes down to the brand name, brand names are more important online than they are in the physical world. Additionally, a beginning with A was preferential due to the probability it would occur at the top of any list that was alphabetized. Since June 19,2000, Amazons logotype has featured a curved arrow leading from A to Z, representing that the company carries every product from A to Z, with the arrow shaped like a smile. After reading a report about the future of the Internet that projected annual Web commerce growth at 2, 300% and he narrowed the list to what he felt were the five most promising products, which included, compact discs, computer hardware, computer software, videos and books. Amazon was founded in the garage of Bezos home in Bellevue, the company began as an online bookstore, an idea spurred off with discussion with John Ingram of Ingram Book, along with Keyur Patel who still holds a stake in Amazon. Amazon was able to access books at wholesale from Ingram, in the first two months of business, Amazon sold to all 50 states and over 45 countries
7.
Ubuntu (operating system)
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Ubuntu is published by Canonical Ltd, who offer commercial support. It uses Unity as its user interface for the desktop. Ubuntu is the most popular operating system running in hosted environments, so–called clouds, development of Ubuntu is led by UK-based Canonical Ltd. a company of South African entrepreneur Mark Shuttleworth. Canonical generates revenue through the sale of technical support and other related to Ubuntu. The Ubuntu project is committed to the principles of open-source software development, people are encouraged to use free software, study how it works, improve upon it. Ubuntu is built on Debians architecture and infrastructure, to provide Linux server, desktop, phone, tablet, the first release was in October 2004. Starting with Ubuntu 6.06, every release, one release every two years, receives long-term support. Long-term support includes updates for new hardware, security patches and updates to the Ubuntu stack. The first LTS releases were supported for three years on the desktop and five years on the server, since Ubuntu 12.04 LTS, LTS releases get regular point releases with support for new hardware and integration of all the updates published in that series to date. Ubuntu packages are based on packages from Debians unstable branch, both distributions use Debians deb package format and package management tools. Debian and Ubuntu packages are not necessarily compatible with each other, however. Many Ubuntu developers are also maintainers of key packages within Debian, Ubuntu cooperates with Debian by pushing changes back to Debian, although there has been criticism that this does not happen often enough. Ian Murdock, the founder of Debian, had expressed concern about Ubuntu packages potentially diverging too far from Debian to remain compatible, before release, packages are imported from Debian unstable continuously and merged with Ubuntu-specific modifications. One month before release, imports are frozen, and packagers then work to ensure that the frozen features interoperate well together, Ubuntu is currently funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical announced the creation of the Ubuntu Foundation, the purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the goal as to ensure the continuity of the Ubuntu project. On 12 March 2009, Ubuntu announced developer support for 3rd-party cloud management platforms, Unity has become the default GUI for Ubuntu Desktop, although following the release of Ubuntu 17.10 it will move to the GNOME3 desktop instead as work on Unity ends. A default installation of Ubuntu contains a range of software that includes LibreOffice, Firefox, Thunderbird, Transmission
8.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and 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, e. g. Solaris, Linux, 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 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 work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and 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 and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a 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, 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 run different programs in succession to speed up processing
9.
MacOS
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Within the market of desktop, laptop and home computers, and by web usage, it is the second most widely used desktop OS after Microsoft Windows. Launched in 2001 as Mac OS X, the series is the latest in the family of Macintosh operating systems, Mac OS X succeeded classic Mac OS, which was introduced in 1984, and the final release of which was Mac OS9 in 1999. An initial, early version of the system, Mac OS X Server 1.0, was released in 1999, the first desktop version, Mac OS X10.0, followed in March 2001. In 2012, Apple rebranded Mac OS X to OS X. Releases were code named after big cats from the release up until OS X10.8 Mountain Lion. Beginning in 2013 with OS X10.9 Mavericks, releases have been named after landmarks in California, in 2016, Apple rebranded OS X to macOS, adopting the nomenclature that it uses for their other operating systems, iOS, watchOS, and tvOS. The latest version of macOS is macOS10.12 Sierra, macOS is based on technologies developed at NeXT between 1985 and 1997, when Apple acquired the company. The X in Mac OS X and OS X is pronounced ten, macOS shares its Unix-based core, named Darwin, and many of its frameworks with iOS, tvOS and watchOS. A heavily modified version of Mac OS X10.4 Tiger was used for the first-generation Apple TV, Apple also used to have a separate line of releases of Mac OS X designed for servers. Beginning with Mac OS X10.7 Lion, the functions were made available as a separate package on the Mac App Store. Releases of Mac OS X from 1999 to 2005 can run only on the PowerPC-based Macs from the time period, Mac OS X10.5 Leopard was released as a Universal binary, meaning the installer disc supported both Intel and PowerPC processors. In 2009, Apple released Mac OS X10.6 Snow Leopard, in 2011, Apple released Mac OS X10.7 Lion, which no longer supported 32-bit Intel processors and also did not include Rosetta. All versions of the system released since then run exclusively on 64-bit Intel CPUs, the heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, and then launched in 1989 and its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. This led Apple to purchase NeXT in 1996, allowing NeXTSTEP, then called OPENSTEP, previous Macintosh operating systems were named using Arabic numerals, e. g. Mac OS8 and Mac OS9. The letter X in Mac OS Xs name refers to the number 10 and it is therefore correctly pronounced ten /ˈtɛn/ in this context. However, a common mispronunciation is X /ˈɛks/, consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API, the consumer version of Mac OS X was launched in 2001 with Mac OS X10.0. Reviews were variable, with praise for its sophisticated, glossy Aqua interface
10.
Debian
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The Debian Project was first announced in 1993 by Ian Murdock, Debian 0.01 was released on September 15,1993, and the first stable release was made in 1996. The Debian stable release branch is one of the most popular for personal computers and network servers, new distributions are updated continually, and the next candidate is released after a time-based freeze. As one of the earliest Operating Systems based on the Linux kernel and this decision drew the attention and support of the Free Software Foundation, which sponsored the project for one year from November 1994 to November 1995. Upon the ending of the sponsorship, the Debian Project formed the non-profit organisation Software in the Public Interest, while Debians main port, Debian GNU/Linux, uses the Linux kernel, other ports exist based on BSD kernels and the HURD microkernel. All use the GNU userland and the GNU C library, Debian has access to online repositories that contain over 50,000 software packages making it one of the largest software compilations. Debian officially contains only free software, but non-free software can be downloaded from the Debian repositories, Debian includes popular free programs such as LibreOffice, Firefox web browser, Evolution mail, K3b disc burner, VLC media player, GIMP image editor, and Evince document viewer. Debian is a choice for web servers. Debian supports Linux officially, offered kFreeBSD for version 7 but not 8, GNU/kFreeBSD was released as a technology preview for IA-32 and x86-64 architectures, and lacked the amount of software available in Debians Linux distribution. Official support for kFreeBSD was removed for version 8, which did not provide a kFreeBSD-based distribution, several flavors of the Linux kernel exist for each port. For example, the port has flavors for IA-32 PCs supporting Physical Address Extension and real-time computing, for older PCs. The Linux kernel does not officially contain firmware without sources, although such firmware is available in non-free packages, Debian offers DVD and CD images for installation that can be downloaded using BitTorrent or jigdo. Physical disks can also be bought from retailers, Debian offers different network installation methods. A minimal install of Debian is available via the netinst CD, whereby Debian is installed with just a base, another option is to boot the installer from the network. Installation images are hybrid on some architectures and can be used to create a bootable USB drive, the default bootstrap loader is GNU GRUB version 2, though the package name is simply grub, while version 1 was renamed to grub-legacy. This conflicts with e. g. Fedora, where grub version 2 is named grub2, the default desktop may be chosen from the DVD boot menu among GNOME, KDE Software Compilation, Xfce and LXDE, and from special disc 1 CDs. Debian offers CD images specifically built for GNOME, KDE Software Compilation, Xfce, MATE is officially supported, while Cinnamon support was added with Debian 8.0 Jessie. Less common window managers such as Enlightenment, Openbox, Fluxbox, IceWM, Window Maker, the default desktop environment of version 7.0 Wheezy was temporarily switched to Xfce, because GNOME3 did not fit on the first CD of the set. The default for the version 8.0 Jessie was changed again to Xfce in November 2013, Debian releases live install images for CDs, DVDs and USB thumb drives, for IA-32 and x86-64 architectures, and with a choice of desktop environments
11.
System administrator
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A system administrator, or sysadmin, is a person who is responsible for the upkeep, configuration, and reliable operation of computer systems, especially multi-user computers, such as servers. The system administrator seeks to ensure that the uptime, performance, resources, many organizations staff other jobs related to system administration. In a larger company, these may all be separate positions within a support or Information Services department. In a smaller group they may be shared by a few sysadmins, a database administrator maintains a database system, and is responsible for the integrity of the data and the efficiency and performance of the system. A network administrator maintains network infrastructure such as switches and routers, a security administrator is a specialist in computer and network security, including the administration of security devices such as firewalls, as well as consulting on general security measures. A web administrator maintains web server services that allow for internal or external access to web sites, tasks include managing multiple sites, administering security, and configuring necessary components and software. Responsibilities may also include software change management, a computer operator performs routine maintenance and upkeep, such as changing backup tapes or replacing failed drives in a redundant array of independent disks. There are multiple paths to be part of becoming a system administrator, on top of this, nowadays some companies require an IT certification. Other schools have offshoots of their Computer Science program specifically for system administration, an alternate path to becoming a system administrator is to simply dive in without formal training, learning the systems they need to support, as they do other non-IT work. This is a route for informally trained system administration, and is often the result in small organizations that lack IT departments but have gradually growing needs. These informally trained system administrators could be regarded as hackers, but they do their work in support of the needs of their organization, some schools have started offering undergraduate degrees in System Administration. The first, Rochester Institute of Technology started in 1992, others such as Rensselaer Polytechnic Institute, University of New Hampshire, Marist College, and Drexel University have more recently offered degrees in Information Technology. Symbiosis Institute of Computer Studies and Research in Pune, India offers masters degree in Computers Applications with a specialization in System Administration, the University of South Carolina offers an Integrated Information Technology B. S. degree specializing in Microsoft product support. Several U. S. universities, including Rochester Institute of Technology, Tufts, Michigan Tech, in Norway, there is a special English-taught MSc program organized by Oslo University College in cooperation with Oslo University, named Masters programme in Network and System Administration. There is also a BSc in Network and System Administration offered by Gjøvik University College, University of Amsterdam offers a similar program in cooperation with Hogeschool van Amsterdam named Master System and Network Engineering. Many schools in the world offer related graduate degrees in such as network systems. By the time a new textbook has spent years working through approvals and committees, in addition, because of the practical nature of system administration and the easy availability of open-source server software, many system administrators enter the field self-taught. Some learning institutions are reluctant to teach, what is in effect, generally, a prospective will be required to have some experience with the computer system they are expected to manage
