Open Source Software

Linux is developed as a cooperative open source effort over the Internet, so no company or institution controls Linux. Software developed for Linux reflects this background.
Development often takes place when Linux users decide to work together on a project. The software is posted at an Internet site, and any Linux user can then access the site and download the software. Linux software development has always operated in an Internet environment and is global in scope, enlisting programmers from around the world. The only thing you need to start a Linux-based software project is a Web site.

Most Linux software is developed as open source software, and the source code for an application is freely distributed along with the application. Programmers over the Internet can make their own contributions to a software package’s development, modifying and correcting the source code, which is included in all its distributions and is freely available on the Internet. Many major software development efforts are also open source projects, as are the KDE and GNOME desktops along with most of their applications. The OpenOffice office suite supported by Sun is an open source project based on the StarOffice office suite (Sun’s commercial version of OpenOffice). You can find more information about the Open Source Initiative at www.opensource.org.

Open source software is protected by public licenses that prevent commercial companies from taking control of the software by adding modifications of their own, copyrighting those changes, and selling the software as their own product. The most popular public license is the GNU GPL, under which Linux is distributed, which is provided by the Free Software Foundation. The GNU GPL retains the copyright, freely licensing the software with the requirement that the software and any modifications made to it are always freely available. Other public licenses have been created to support the demands of different kinds of open source projects. The GNU Lesser General Public License (LGPL) lets commercial applications use GNU-licensed software libraries. The Qt Public License (QPL) lets open source developers use the Qt libraries essential to the KDE desktop. You can find a complete listing at www.opensource.org.

Linux is currently copyrighted under a GNU public license provided by the Free Software Foundation, and it is often referred to as GNU software (see www.gnu.org). GNU software is distributed free, provided it is freely distributed to others. GNU software has proved both reliable and effective. Many of the popular Linux utilities, such as C compilers, shells, and editors, are GNU software applications. Installed with your Linux distribution are the GNU C++ and Lisp compilers, Vi and Emacs editors, BASH and TCSH shells, as well as TeX and Ghostscript document formatters. In addition, many open source software projects are licensed under the GNU GPL. Most of these applications are available on the Ubuntu software repositories. Under the terms of the GNU GPL, the original author retains the copyright, although anyone can modify the software and redistribute it, provided the source code is included, made public, and provided free. Also, no restriction exists on selling the software or giving it away free.

One distributor could charge for the software, while another could provide it free of charge. Major software companies are also providing Linux versions of their most popular applications. Oracle provides a Linux version of its Oracle database. (At present, no plans seem in the works for Microsoft applications, though you can use the Wine, the Windows compatibility layer, to run many Microsoft applications on Linux, directly.)

Source of Information : McGraw Hill Ubuntu The Complete Reference