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The development of Linux is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License. Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Some popular mainstream Linux distributions include Debian (and its derivatives such as Ubuntu), Fedora and openSUSE. Linux distributions include the Linux kernel and supporting utilities and libraries to fulfill the distribution's intended use.
Commonly used applications with desktop Linux systems include thMozilla Firefoxe web-browser, the office application suite and the GIMP image editor.
A Linux-based system is a modular Unix-like operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running.
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 by far the most widely used. Some free and open source software licenses are based on the principle of copyleft, a kind of reciprocity: any work derived from a copyleft piece of software must also be copyleft itself. The most common free software license, the GNU GPL, is a form of copyleft, and is used for the Linux kernel and many of the components from the GNU project.



OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995. The project is widely known for the developers' insistence on open source code and quality documentation, uncompromising position on software licensing, and focus on security and code correctness.
On 25 July 2007, OpenBSD developer Bob Beck announced the formation of the OpenBSD Foundation,a Canadian not-for-profit corporation formed to "act as a single point of contact for persons and organizations requiring a legal entity to deal with when they wish to support OpenBSD."

A goal of the OpenBSD project is to "maintain the spirit of the original Berkeley Unix copyrights", which permitted a "relatively un-encumbered Unix source distribution".To this end, the Internet Systems Consortium licence, a simplified version of the BSD licence with wording removed that is unnecessary under the Berne convention, is preferred for new code, but the MIT or BSD licences are accepted. The widely used GNU General Public License is considered overly restrictive incomparison .


open Solaris

OpenSolaris is an open source computer operating system based on Solaris created by Sun Microsystems, now a part of Oracle Corporation. It was also the name of the project initiated by Sun to build a developer and user community around the software. After the acquisition of Sun Microsystems, Oracle decided to discontinue open development of the core software, and replaced the OpenSolaris distribution model with the commercial Solaris Express.
OpenSolaris is a descendant of the UNIX System V Release 4 (SVR4) codebase developed by Sun and AT&T in the late 1980s. It is the only version of the System V variant of UNIX available as open source.OpenSolaris is developed as a combination of several software consolidations which were open sourced subsequent to Solaris 10.
OpenSolaris is offered as both development (unstable) and production (stable) releases.
Development releases are built from the latest OpenSolaris codebase (consolidations) and include newer technologies, security updates and bug fixes, and more applications, but may not have undergone extensive testing.
Production releases are branched from a snapshot of the development codebase (following a code freeze) and undergo a QA process that includes backporting security updates and bug fixes.
OpenSolaris uses a network-aware package management system called the Image Packaging System (also known as pkg(5)) to add, remove, and manage installed software and to update to newer releases.