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wanted, etc etc... What is GNU/Linux? The Unix operating system was conceived and implemented in the 1960s and first released in 1970. Its wide availability and portability
meant that it was widely adopted, copied and modified by academic
institutions and businesses, with its design being influential on
authors of other systems.
The GNU Project, started in 1984, had the goal of creating a "complete Unix-compatible software system"[5] made entirely of free software. In 1985, Richard Stallman created the Free Software Foundation and developed the GNU General Public License (GNU GPL). Many of the programs required in an OS (such as libraries, compilers, text editors, a Unix shell, and a windowing system) were completed by the early 1990s, although low level elements such as device drivers, daemons, and the kernel were stalled and incomplete.[6]
Linus Torvalds has said that if the GNU kernel had been available at
the time (1991), he would not have decided to write his own.[7]
MINIX, a Unix-like system intended for academic use, was released by Andrew S. Tanenbaum
in 1987. While source code for the system was available, modification
and redistribution were restricted (that is not the case today). In
addition, MINIX's 16-bit design was not well adapted to the 32-bit design of the increasingly cheap and popular Intel 386 architecture for personal computers.
In 1991, Torvalds began to work on a non-commercial replacement for MINIX while he was attending the University of Helsinki.[8] This eventually became the Linux kernel.
In 1992, Tanenbaum posted an article on Usenet claiming Linux was obsolete. In the article, he criticized the operating system as being monolithic in design and being tied closely to the x86 architecture and thus not portable, as he described "a fundamental error."[9] Tanenbaum suggested that those who wanted a modern operating system should look into one based on the microkernel model. The posting solicited the response of Torvalds and Ken Thompson, one of the founders of Unix, which resulted in a well known debate over the microkernel and monolithic kernel designs.[9]
Linux was dependent on the MINIX userspace
at first. With code from the GNU system freely available, it was
advantageous if this could be used with the fledgling OS. Code licensed
under the GNU GPL can be used in other projects, so long as they also
are released under the same or a compatible license. In order to make
the Linux kernel compatible with the components from the GNU Project,
Torvalds initiated a switch from his original license (which prohibited
commercial redistribution) to the GNU GPL.[10] Linux and GNU developers worked to integrate GNU components with Linux to make a fully functional and free operating system.[6]
[edit] Commercial and popular uptake
Today Linux is used in numerous domains, from embedded systems[11] to supercomputers,[12] and has secured a place in server installations with the popular LAMP application stack.[13]
Torvalds continues to direct the development of the kernel. Stallman
heads the Free Software Foundation, which in turn supports the GNU
components. Finally, individuals and corporations develop third-party
non-GNU components. These third-party components comprise a vast body
of work and may include both kernel modules and user applications and
libraries. Linux vendors and communities combine and distribute the
kernel, GNU components, and non-GNU components, with additional package
management software in the form of Linux distributions.
[edit] Design
Linux is a modular Unix-like
operating system. It derives much of its basic design from principles
established in Unix during the 1970s and 1980s. Linux uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are integrated directly with the kernel.
Much of Linux's higher-level functionality is provided by separate projects which interface with the kernel. The GNU userland is an important part of most Linux systems, providing the shell and Unix tools which carry out many basic operating system tasks. On top these tools form a Linux system with a graphical user interface that can be used, usually running in the X Window System.
[edit] User interface
- See also: User interface
Linux can be controlled by one or more of a text-based command line interface (CLI), graphical user interface (GUI) (usually the default for desktop), through controls on the device itself (common on embedded machines).
On desktop machines, KDE, GNOME and Xfce are the most popular user interfaces,[14] though a variety of other user interfaces exist. Most popular user interfaces run on top of the X Window System (X), which provides network transparency, enabling a graphical application running on one machine to be displayed and controlled from another.
Other GUIs include X window managers such as FVWM, Enlightenment and Window Maker.
The window manager provides a means to control the placement and
appearance of individual application windows, and interacts with the X
window system.
A Linux system usually provides a CLI of some sort through a shell,
which is the traditional way of interacting with a Unix system. A Linux
distribution specialized for servers may use the CLI as its only
interface. A “headless system” run without even a monitor can be
controlled by the command line via a protocol such as SSH or telnet.
Most low-level Linux components, including the GNU Userland,
use the CLI exclusively. The CLI is particularly suited for automation
of repetitive or delayed tasks, and provides very simple inter-process communication. A graphical terminal emulator program is often used to access the CLI from a Linux desktop.
[edit] Development
-
A graphical history of Unix systems. Linux is a Unix-type system but its source code does not descend from the original Unix.
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 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,[15] SUS,[16] ISO, and ANSI standards where possible, although to date only one Linux distribution has been POSIX.1 certified, Linux-FT.[17]
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.
[edit] Community
A command line session using bash
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. 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 the Linux kernel and its relationship
with GNU on the GNU project's website. Print magazines on Linux often include cover disks including software or even complete Linux distributions.[18][19]
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.
Desktop
-
Main article: Desktop Linux
KDE 3.5, showing the Kontact personal information manager and Konqueror file manager, web browser, and file viewer.
Although in specialized application domains such as desktop publishing and professional audio
there may be a lack of high quality software, users migrating from Mac
OS X and Windows can find equivalent applications for most tasks.[23]
Many free software titles that are popular on Windows are also available, such as Pidgin, Mozilla Firefox, Openoffice.org, and GIMP, amongst others. A growing amount of proprietary desktop software is also supported under Linux,[24] examples being Adobe Flash Player, Acrobat Reader, Matlab, Nero Burning ROM, Opera, RealPlayer, and Skype.
In the field of animation and visual effects, most high end software,
such as AutoDesk Maya, Softimage XSI and Apple Shake are available both
for Linux, Windows and/or MacOS X. Additionally, CrossOver is a proprietary solution based on the open source Wine project that supports running older, superseded Windows versions of Microsoft Office and Adobe Photoshop. (Microsoft Office 2007 and Adobe Photoshop CS are known not to work,[25][26] while Adobe Photoshop CS2 and CS3 are untested and unsupported.[27][28])
Linux's open nature offers the ability for distributed teams to localize Linux distributions for use in locales where doing so to proprietary systems would not be cost-effective. For example, the Sinhalese language version of the Knoppix distribution was available for a long time before the initiation of translation of Microsoft Windows XP
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.
- See also: Linux gaming
[edit] Servers and supercomputers
Historically, Linux has mainly been used as a server operating system, and has risen to prominence in that area; Netcraft reported in September 2006 that eight of the ten most reliable internet hosting companies run Linux on their web servers.[29]
This is due to its relative stability and long uptime, and the fact
that desktop software with a graphical user interface is often
unneeded. Enterprise and non-enterprise Linux distributions may be
found running on servers. Linux is the cornerstone of the LAMP server-software combination (Linux, Apache, MySQL, Perl/PHP/Python) which has achieved popularity among developers, and which is one of the more common platforms for website hosting.
Linux is commonly used as an operating system for supercomputers. As of November 2007, out of the top 500 systems, 426 (85.2%) run Linux.[30]
[edit] Embedded devices
-
Main article: embedded Linux
Due to its low cost and ability to be easily modified, an embedded Linux is often used in embedded systems. Linux has become a major competitor to the proprietary Symbian OS found in many mobile phones — 16.7% of smartphones sold worldwide during 2006 were using Linux[31] — and it is an alternative to the dominant Windows CE and Palm OS operating systems on handheld devices. The popular TiVo digital video recorder uses a customized version of Linux.[32] Several network firewall and router standalone products, including several from Linksys, use Linux internally, using its advanced firewall and routing capabilities. The Korg OASYS and the Yamaha Motif XS music workstations also run Linux.[33]
[edit] Market share and uptake
GNOME 2.16, showing the Nautilus file manager and the gedit text editor.
-
Main article: Linux adoption
Many quantitative studies of open source software focus on topics
including market share and reliability, with numerous studies
specifically examining Linux.[34]
The Linux market is growing rapidly, and the revenue of servers,
desktops, and packaged software running Linux is expected to exceed
$35.7 billion by 2008.[35]
IDC's report for Q1 2007 says that Linux now holds 12.7% of the overall server market.[36] This estimate was based on the number of Linux servers sold by various companies. What is BSD? Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995.
Historically, BSD has been considered a branch of UNIX — "BSD UNIX",
because it shared the initial codebase and design with the original AT&T UNIX operating system. In the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary UNIX variants such as DEC ULTRIX and Sun Microsystems SunOS.
This can be attributed to the ease with which it could be licensed, and
the familiarity it found among the founders of many technology
companies of this era.
Though these commercial BSD derivatives were largely superseded by the UNIX System V Release 4 and OSF/1 systems in the 1990s (both of which incorporated BSD code), later BSD releases provided a basis for several open source development projects which continue to this day.
Today, the term of "BSD" is often non-specifically used to refer to any of these BSD descendants, e.g. FreeBSD, NetBSD or OpenBSD, which together form a branch of the family of Unix-like operating systems.
[edit] History
Evolution of Unix systems
[edit] PDP-11 beginnings
The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify and extend Unix. The first Unix system at Berkeley was a PDP-11 installed in 1974, and the computer science department used it for extensive research thereafter.
Other universities became interested in the software at Berkeley, and so in 1977 Bill Joy, then a graduate student at Berkeley, assembled and sent out tapes of the first Berkeley Software Distribution (1BSD). 1BSD was an add-on to Sixth Edition Unix rather than a complete operating system in its own right; its main components were a Pascal compiler and Joy's ex line editor.
The Second Berkeley Software Distribution (2BSD),
released in 1978, included updated versions of the 1BSD software as
well as two new programs by Joy that persist on Unix systems to this
day: the vi text editor (a visual version of ex) and the C shell.
Later releases of 2BSD contained ports of changes to the VAX-based
releases of BSD back to the PDP-11 architecture. 2.9BSD from 1983
included code from 4.1cBSD, and was the first release that was a full
OS (a modified Version 7 Unix) rather than a set of applications and patches. The most recent release, 2.11BSD,
was first released in 1992. As of 2008, maintenance updates from
volunteers are still continuing, with patch 447 being released on
December 31, 2008.[1]
[edit] VAX versions
A VAX computer was installed at Berkeley in 1978, but the port of Unix to the VAX architecture, UNIX/32V, did not take advantage of the VAX's virtual memory capabilities. The kernel of 32V was largely rewritten by Berkeley students to include a virtual
memory implementation, and a complete operating system including the
new kernel, ports of the 2BSD utilities to the VAX, and the utilities
from 32V was released as 3BSD at the end of 1979. 3BSD was also
alternatively called Virtual VAX/UNIX or VMUNIX (for Virtual Memory
Unix), and BSD kernel images were normally called /vmunix until 4.4BSD.
The success of 3BSD was a major factor in the Defense Advanced Research Projects Agency's (DARPA) decision to fund Berkeley's Computer Systems Research Group (CSRG), which would develop a standard Unix platform for future DARPA research in the VLSI Project. CSRG released 4BSD, containing numerous improvements to the 3BSD system, in October 1980.
4BSD (November 1980) offered a number of enhancements over 3BSD, notably job control in the previously released csh, delivermail (the antecedent of sendmail), "reliable" signals, and the Curses programming library.
4.1BSD (June 1981) was a response to criticisms of BSD's performance relative to the dominant VAX operating system, VMS. The 4.1BSD kernel was systematically tuned up by Bill Joy until it could perform as well as VMS on several benchmarks. (The release would have been called 5BSD, but after objections from AT&T the name was changed; AT&T feared confusion with AT&T's UNIX System V.[2] One early, never-released test version was in fact called 4.5BSD.)
4.2BSD would take over two years to implement and contained
several major overhauls. Before its official release came three
intermediate versions: 4.1a incorporated a modified version of BBN's preliminary TCP/IP implementation; 4.1b included the new Berkeley Fast File System, implemented by Marshall Kirk McKusick; and 4.1c was an interim release during the last few months of 4.2BSD's development.
To guide the design of 4.2BSD Duane Adams of DARPA formed a "steering committee" consisting of Bob Fabry, Bill Joy and Sam Leffler from UCB, Alan Nemeth and Rob Gurwitz from BBN, Dennis Ritchie from Bell Labs, Keith Lantz from Stanford, Rick Rashid from Carnegie-Mellon, Bert Halstead from MIT, Dan Lynch from ISI, and Gerald J. Popek of UCLA. The committee met from April 1981 to June 1983.
The official 4.2BSD release came in August 1983. It was notable as
the first version released after the 1982 departure of Bill Joy to
co-found Sun Microsystems; Mike Karels and Marshall Kirk McKusick took on leadership roles within the project from that point forward. On a lighter note, it also marked the debut of BSD's daemon mascot in a drawing by John Lasseter that appeared on the cover of the printed manuals distributed by USENIX.
[edit] 4.3BSD
4.3BSD was released in June 1986. Its main changes were to
improve the performance of many of the new contributions of 4.2BSD that
had not been as heavily tuned as the 4.1BSD code. Prior to the release,
BSD's implementation of TCP/IP had diverged considerably from BBN's
official implementation. After several months of testing, DARPA
determined that the 4.2BSD version was superior and would remain in
4.3BSD. (See also History of the Internet.)
After 4.3BSD, it was determined that BSD would move away from the aging VAX platform. The Power 6/32 platform (codenamed "Tahoe") developed by Computer Consoles Inc. seemed promising at the time, but was abandoned by its developers shortly thereafter. Nonetheless, the 4.3BSD-Tahoe port (June 1988) proved valuable as it led to a separation of
machine-dependent and machine-independent code in BSD which would
improve the system's future portability.
Apart from portability, the CSRG worked on an implementation of the OSI network protocol stack, improvements to the kernel virtual memory system and (with Van Jacobson of LBL) new TCP/IP algorithms to accommodate the growth of the internet.[3]
Until this point, all versions of BSD incorporated proprietary
AT&T Unix code and were therefore subject to an AT&T software
license. Source code licenses had become very expensive by this point,
and several outside parties had expressed interest in a separate
release of the networking code, which had been developed entirely
outside AT&T and would not be subject to the licensing requirement.
This led to Networking Release 1 (Net/1), which was made available to non-licensees of AT&T code and was freely redistributable under the terms of the BSD license. It was released in June 1989.
4.3BSD-Reno came in early 1990. It was an interim release
during the early development of 4.4BSD, and its use was considered a
"gamble", hence the naming after the gambling center of Reno, Nevada. This release was explicitly moving towards POSIX compliance,[3] and, according to some, away from the BSD philosophy (as POSIX is very
much based on System V, and Reno was quite bloated compared to previous
releases). Among the new features was an NFS implementation from the University of Guelph.
In August 2006, Information Week magazine rated 4.3BSD as the "Greatest Software Ever Written".[4] They commented: "BSD 4.3 represents the single biggest theoretical undergirder of the Internet."
[edit] Net/2 and legal troubles
After Net/1, BSD developer Keith Bostic proposed that more non-AT&T sections of the BSD system be released
under the same license as Net/1. To this end, he started a project to
reimplement most of the standard Unix utilities without using the
AT&T code. For example, vi, which had been based on the original Unix version of ed, was rewritten as nvi (new vi). Within eighteen months, all the AT&T utilities had been
replaced, and it was determined that only a few AT&T files remained
in the kernel. These files were removed, and the result was the June
1991 release of Networking Release 2 (Net/2), a nearly complete operating system that was freely distributable.
Net/2 was the basis for two separate ports of BSD to the Intel 80386 architecture: the free 386BSD by William Jolitz and the proprietary BSD/386 (later renamed BSD/OS) by Berkeley Software Design (BSDi). 386BSD itself was short-lived, but became the initial code base of the NetBSD and FreeBSD projects that were started shortly thereafter.
BSDi soon found itself in legal trouble with AT&T's Unix System Laboratories subsidiary, then the owners of the System V copyright and the Unix trademark. The USL v. BSDi lawsuit was filed in 1992 and led to an injunction on the distribution of Net/2 until the validity of USL's copyright claims on the source could be determined.
The lawsuit slowed development of the free-software descendants of
BSD for nearly two years while their legal status was in question, and
as a result systems based on the Linux kernel, which did not have such legal ambiguity, gained greater support. Although not released until 1992, development of 386BSD predated that of Linux, and Linus Torvalds has said that if 386BSD had been available at the time, he probably would not have created Linux.[5]
[edit] 4.4BSD and descendants
The lawsuit was settled in January 1994, largely in Berkeley's
favor. Of the 18,000 files in the Berkeley distribution, only 3 had to
be removed and 70 modified to show USL copyright notices. A further
condition of the settlement was that USL would not file further
lawsuits against users and distributors of the Berkeley-owned code in
the upcoming 4.4BSD release.
In June 1994, 4.4BSD was released in two forms: the freely distributable 4.4BSD-Lite contained no AT&T source, whereas 4.4BSD-Encumbered was available, as earlier releases had been, only to AT&T licensees.
The final release from Berkeley was 1995's 4.4BSD-Lite Release 2,
after which the CSRG was dissolved and development of BSD at Berkeley
ceased. Since then, several variants based directly or indirectly on
4.4BSD-Lite (such as FreeBSD, NetBSD, OpenBSD and DragonFly BSD) have been maintained.
In addition, the permissive nature of the BSD license has allowed
many other operating systems, both free and proprietary, to incorporate
BSD code. For example, Microsoft Windows has used BSD-derived code in its implementation of TCP/IP and bundles recompiled versions of BSD's command-line networking tools with its current releases.[6] Also Darwin, the system on which Apple's Mac OS X is built, is partly derived from 4.4BSD-Lite2 and FreeBSD. Various commercial UNIXes, such as Solaris, also contain varying amounts of BSD code.
[edit] Technology
BSD pioneered many of the advances of modern computing. Berkeley's Unix was the first Unix to include libraries supporting the Internet Protocol stacks: Berkeley sockets. By integrating sockets with the Unix operating system's file descriptors, it became almost as easy to read and write data across a network as it was to access a disk. The AT&T laboratory eventually released their own STREAMS library, which incorporated much of the same functionality in a
software stack with a better architecture, but the wide distribution of
the existing sockets library, together with the unfortunate omission of
a function call for polling a set of open sockets equivalent to the select call in the Berkeley library, reduced the impact of the new API. Early versions of BSD were used to form Sun Microsystems' SunOS, founding the first wave of popular Unix workstations.
Today, BSD continues to be used as a testbed for technology by
academic organizations, as well as finding uses in a lot of commercial
and free products and, increasingly, in embedded devices.
The general quality of its source code, as well as its documentation
(especially reference manual pages, commonly referred to as man pages), make it well-suited for many purposes.
The permissive nature of the BSD license allows companies to distribute derived products as proprietary software without exposing source code and sometimes intellectual property to competitors. Searching for strings containing "University of
California, Berkeley" in the documentation of products, in the static
data sections of binaries and ROMs,
or as part of other information about a software program, will often
show BSD code has been used. This permissiveness also makes BSD code
suitable for use in open source products, and the license is compatible with many other open source licenses.
BSD operating systems can run much native software of several other operating systems on the same architecture, using a binary compatibility layer. Much simpler and faster than emulation, this allows, for instance, applications intended for Linux to be run at effectively full speed. This makes BSDs not only suitable
for server environments, but also for workstation ones, given the
increasing availability of commercial or closed-source software for
Linux only. This also allows administrators to migrate legacy
commercial applications, which may have only supported commercial Unix
variants, to a more modern operating system, retaining the
functionality of such applications until they can be replaced by a
better alternative.
Current BSD operating system variants support many of the common IEEE, ANSI, ISO, and POSIX standards, while retaining most of the traditional BSD behavior. Like AT&T Unix, the BSD kernel is monolithic, meaning that device drivers in the kernel run in privileged mode, as part of the core of the operating system.
[edit] Significant BSD descendants
Bar chart showing the proportion of users of each BSD variant from a BSD usage survey in 2005. [7] Each participant was permitted to indicate multiple BSD variants
- See also: Category:BSD and Comparison of BSD operating systems
BSD has been the base of a large number of operating systems. Most notable among these today are perhaps the major open source BSDs: FreeBSD, NetBSD and OpenBSD, which are all derived from 386BSD and 4.4BSD-Lite
by various routes. Both NetBSD and FreeBSD started life in 1993,
initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite
code base. OpenBSD was forked in 1995 from NetBSD. The three most notable descendants in current use —sometimes known as the BSDs— have themselves spawned a number of children, including DragonFly BSD, FreeSBIE, MirOS BSD, DesktopBSD, and PC-BSD.
They are targeted at an array of systems for different purposes and are
common in government facilities, universities and in commercial use. A
number of commercial operating systems are also partly or wholly based
on BSD or its descendants, including Sun's SunOS and Apple Inc.'s Mac OS X.
Most of the current BSD operating systems are open source and available for download, free of charge, under the BSD License, the most notable exception being Mac OS X. They also generally use a monolithic kernel architecture, apart from Mac OS X and DragonFly BSD which feature hybrid kernels. The various open source BSD projects generally develop the kernel and userland programs and libraries together, the source code being managed using a single central source repository.
In the past, BSD was also used as a basis for several proprietary versions of UNIX, such as Sun's SunOS, Sequent's Dynix, NeXT's NeXTSTEP, DEC's Ultrix and OSF/1 AXP (now Tru64 UNIX).
Of these, only the last is still currently supported in its original
form. Parts of NeXT's software became the foundation for Mac OS X, among the most commercially successful BSD variants in the general market.
A selection of significant Unix versions and Unix-like operating systems that descend from BSD includes:
- FreeBSD, a major open source effort focusing on performance and the x86 platform.
- DragonFly BSD, a fork of FreeBSD to follow an alternative design, particularly related to SMP.
- PC-BSD and DesktopBSD, distributions of FreeBSD with emphasis on ease of use and user friendly interfaces for the desktop/laptop PC user.
- Nokia IPSO (IPSO SB variant), the FreeBSD-based OS used in Nokia Firewall Appliances.
- Juniper Networks JunOS, the operating system for Juniper routers, a customized version
of FreeBSD, and a variety of other embedded operating systems
- Apple Inc.'s Darwin, the core of Mac OS X; built on the XNU kernel (part Mach, part FreeBSD, part Apple-derived code) and a userland much of which comes from FreeBSD
- NetBSD, an open source BSD with an emphasis on portability and clean design.
- OpenBSD, a 1995 fork of NetBSD, focuses on portability, standardization, correctness, proactive security and integrated cryptography.
- F5 Networks, All F5 BIGIP Appliances use Free BSD as the underlying OS.
- DEC's Ultrix, the official version of Unix for its PDP-11, VAX, and DECstation systems
- OSF/1, a microkernel-based UNIX developed by the Open Software Foundation, incorporating the Mach kernel and parts of 4BSD
- Early versions of Sun Microsystems SunOS (up to SunOS 4.1.4), an enhanced version of 4BSD for the Sun Motorola 68k-based Sun-2 and Sun-3 systems, SPARC-based systems, and x86-based Sun386i systems.
- NeXT NEXTSTEP and OPENSTEP, based on the Mach kernel and 4BSD; the ancestor of Mac OS X
- 386BSD, the first open source BSD-based operating system and the ancestor of most current BSD systems
- DEMOS, a Soviet BSD clone
- BSD/OS, a (now defunct) proprietary BSD for PCs
What is Ubuntu Linux? About Ubuntu
Ubuntu is a community developed, linux-based operating system that
is perfect for laptops, desktops and servers. It contains all the
applications you need - a web browser, presentation, document and
spreadsheet software, instant messaging and much more.
Learn more about Ubuntu »
The Ubuntu Promise
- Ubuntu will always be free of charge, including enterprise releases and security updates.
- Ubuntu comes with full commercial support from Canonical and hundreds of companies around the world.
- Ubuntu includes the very best translations and accessibility infrastructure that the free software community has to offer.
- Ubuntu CDs contain only free software applications; we encourage
you to use free and open source software, improve it and pass it on.
Read more about the Ubuntu philosophy
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How To Sell To list your item simply click on the “Sell” link found on the header navigational bar. The listing process is split up into several main sections, notably:-
- Category selection
- Item Details
- Auction Settings
- Shipping and Payment
- Listing preview
- Listing confirmation
The listing process is developed in such a way that you are guided through every step seamlessly.
The first part of the process is to choose the category you wish to list your item in, this can be revised at any time by using the “Previous Step” navigation button.
Step two enables you to enter your item title and description, a full wysiwyg editor is in place to enable you to use HTML descriptions.
If you have a voucher code to redeem this can be entered just below the description field.
Moving on to step three, this is the biggest stage of the listing process. On this step you can set the following:-
· Auction type:-
Standard Auction
This is a single quantity auction
Dutch Auction
Dutch auction enables you to list a multiple quantity auction, for example if you have 100 pens to sell you can list all of these together in a single lot. Bidders will be able to select how many they wish to bid for.
· Currency:-
You can select your preferred auction currency using the drop down menu available
· Quantity:-
This field is only active if listing a Dutch auction, please see above for an explanation of this listing type
· Auction Starts At:-
This requires you to enter the minimum bid you are willing to accept, you can also set a reserve price to ensure you do not sell the item for this amount. Please see below for more information on this.
· Reserve Price:-
Enabling a reserve price affectively means you will not sell the item for less than the amount set, for example you can set the start price at 5.00 but only accept winning bids over 50.00, should a bid be placed for 49.99 the item will close without a winner.
· Buy out (if available):-
Buy out allows you to set an amount you are willing to sell the item for – straight out. For example you can set the start price to 10.00 but offer interested parties the option to buy the item immediately for 100.00.
You can also list buy out only auctions, these auctions remove all bidding options meaning the listing can only be purchased for a set amount. To set a buy out only auction you need to set the buy out value to be exactly equal with the start bid.
· Offer-Range (if available):-
You can set a price bracket in which you are willing to listing to offer, for example if you set the price brackets from 15.00 to 100.00 interested parties will be able to offer you an amount within these brackets, you can opt whether to accept or decline these offers at any time via the members area.
· Bid increment:-
This option can be used to set your own custom bid increment if preferred.
· Item featuring (if available):-
The following options are available to you (fees may apply), these will highlight your item on site to ensure they reach more visitors:-
§ Home page featured
§ Category featured
§ Bold text
§ Highlighted background
· Set start/end time:-
You can either opt to list your item right away and set a defined number of days for it to be live for or you also have the option to define your own custom start/end time.
· Private Auction:-
Private auction will hide the bidders identity on the item details page
· Image upload:-
To accompany your item you can either upload images from your local computer or enter the URL of an image(s) hosted elsewhere
· Media upload:-
In addition to images you can also upload media files, please note only .avi/.mpeg/.mov are supported.
· Auto Re-List
For convenience you can opt to have your items automatically re-listed for you, options are available to allow you to select whether the item should be re-listed if sold and how many re-list attempts should be made.
On the next step you can set your shipping and payment preferences including your shipping rates and available methods of delivery.
Proceeding on, you can then review the listing and make changes if required, please note you can still edit your listing once live via the members area. The final step provides you with listing confirmation. Auction Watch The auction watch features notifies you of newly listed auctions which contain keywords you have chosen. For example if you are looking for a new Digital Camera you could enter in those keywords from within your members area area. Each time a new auction is listed containing those keywords you will be notified via email. Item Watching The item watch features lets you keep a close eye on any auction without having to place a bid on it. This feature means you can be kept up to date on how an auction is doing and prepares you to place a winning last minute bid. You can watch any auction by clicking on the “Watch this item” link on any auction page. Buy Out If the option is available you can use “Buy Out” to purchase the item immediately without having to place a bid. Some sellers offer such an option which can be used at any time until a bid has been placed over any applicable reserve price.
The “Buy Out” option will appear on the item details page, you will be asked to confirm your intention to buy out the item before the sale is concluded. Buy out’s cannot be retracted. Registration To create your account choose the “Register” link on the header navigational bar or use any of the links available on the home page.
When registering you will be asked to complete a short form which includes standard information such as your contact details, preferred login credentials etc.
Mandatory fields include:-
· Name
· City
· State/Province/county
· Zip/Post Code
· Phone Number
· Birthday
· Username & Password
· E-Mail address
· Confirmation of terms an conditions acceptance
Once registered you will receive E-Mail confirmation.
Should you encounter any registration difficulties please contact us. Placing A Bid Placing a bid on an item you are interested in couldn’t be easier, when viewing the item details page you will have two areas from where you can place your bid, one next to the item details and a second at the bottom of the page.
To place your bid simply enter the amount you wish to bid e.g. 50.00. Please note no currency symbols are required. The bid will be placed in the auction currency.
Once done you will be asked to review your bid and you will also be able to view vital item details such as the shipping conditions before confirming your bid. To submit your bid simply press the “Place Bid” button.
If your bid is high enough to take the lead in the auction a confirmation message will be displayed to you, however if your bid has not taken the lead be it due to a higher proxy bid or not meeting the reserve price you will be invited to make a further bid.
Should you decide to retract your bid this can be done via the “Current Bids” section of the member’s area.
You can also place a proxy bid, proxy bidding allows you to place your “High Bid”. At all times you will only pay the lowest required bid should you win the auction. For example, if the current bid on an auction is 500.00 you can place a proxy bid of 2,000. Should you remain the only bidder you will only pay 500.00. However should the item receive other bids the site will automatically re-bid for you (upto 2,000 in this scenario) to ensure you remain in the lead. |