Linux and open source software
Software projects take the form of source code, which is a human-readable set of computer instructions. Since source code is not understood directly by the computer, it must be compiled into machine instructions by a compiler. The compiler is a special program that gathers all of the source code files and generates instructions that can be run on the computer, such as by the Linux kernel.
Historically, commercial software has been sold under a closed source license, meaning that users have the right to use the machine code, also known as the binary or executable, but cannot see the source code. Often the license explicitly states that users may not attempt to reverse engineer the machine code back to source code to figure out what it does.
The development of Linux closely parallels the rise of open source software. Early on there was shareware, freely available programs where users did not necessarily have access to the source code. There were a lot of good things about this, but it was also problematic because malicious programs could be disguised as innocent-looking games, screensavers, and utilities.
Open source takes a source-centric view of software. The open source philosophy is that users have the right to obtain the software source code, and to expand and modify programs for their own use. This also meant the code could be inspected for backdoors, viruses, and spyware. By creating a community of developers and users, accountability for bugs, security vulnerabilities, and compatibility issues became a shared responsibility. This new, global community of computer enthusiasts was empowered by the growing availability of faster internet services and the world wide web.
There are many different variants of open source, but all agree that users should have access to the source code. Where they differ is in how one can, or must, redistribute changes.
Linux has adopted this philosophy to great success. Since Linux was written in the C programming language, and it mirrored the design and functionality of already established UNIX systems, it naturally became a forum where people could develop and share new ideas. Freed from the constraints of proprietary hardware and software platforms, large numbers of very skilled programmers have been able to contribute to the various distributions, making for software that is often more robust, stable, adaptable, and, frankly, better than the proprietary, closed source offerings which dominated the previous decades.
Large organizations were understandably suspicious about using software built in this new way, but over time they realized their best programmers were working on Linux-based open source projects in their spare time. Soon, Linux servers and open source programs began to outperform the expensive, proprietary systems already in place. When it came time to upgrade outdated hardware the same programmers, engineers, and system administrators who had started working on Linux as a hobby were able to convince their bosses to give Linux a try. The rest is, as they say, history.
Before the development of Linux, many corporate and scientific applications ran on proprietary UNIX systems. Companies, universities, and governments that run large server farms liked the stability and relative ease of application development these platforms offered.
UNIX was initially created in 1969. By its fourth edition, in 1973, it had been rewritten in the C programming language that is still prominent today. In 1984 the University of California Berkeley released 4.2BSD which introduced TCP/IP, the networking specification that underpins the Internet. By the early 1990’s, when Linux development started, different companies developing UNIX operating systems realized their systems needed to be compatible, and they started working on the X/Open specification that is still used today.
Over the years, computer scientists and the organizations that employ them have realized the benefit of systems that provide familiar tools and consistent ways of accomplishing specific tasks. The standardization of application programming interfaces (APIs) allows programs written for one specific UNIX or Linux operating system to be ported (converted) relatively easy to run on another. So, while proprietary UNIX systems are still in use throughout the world in environments where “certified” solutions are preferred, the interoperability of these systems alongside Linux computers is valued by industry, academia, and governments that use them.
The importance of standards organizations cannot be overstated. Groups like the IEEE (Institute of Electrical and Electronics Engineers) and POSIX (Portable Operating System Interface), allow professionals from different companies and institutions to collaborate on specifications that make it possible for different operating systems and programs to work together. It doesn’t matter if a program is closed or open source, simple or complex, if it is written to these standards others will be able to use and modify it in the future. Every innovation in computing is built on the work of others who came before. Open source software is a collaboration of different people with different needs and backgrounds all working together to make something better than any one of them could have made individually. Standards are what makes this possible, and the many organizations that create, maintain and promote them are integral to the industry.