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The UNIX® Standard


In today’s diverse computing environments, a strong operating system (OS) foundation is needed to drive business continuity and scalability. UNIX®, an open standard owned and managed by The Open Group, is an enabler of key technologies and delivers reduced total cost of ownership, increased IT agility, stability, and interoperability in hetero¬geneous environments enabling business and market innovation across the globe. This OS has an interesting history while showcasing a robust modern market momentum. Download the UNIX Overview Brief today.

UNIX: An Innovative History

The history of computing would not be complete without the vision of Ken Thompson and Dennis Ritchie. Both men couldn’t have anticipated the impact of their contribution to the IT industry in 1969. Thompson, Ritchie, and others at Bell Labs created a collaborative programming environment that would promote what is now commonly called “open development”.

The success of the UNIX approach led to a large number of “look-alike” operating systems, often divergent in compatibility and interoperability. To address this, vendors and users joined together in the 1980s to create the POSIX® standard and later the Single UNIX Specification. Formal UNIX certification started in 1995, with all the major UNIX vendors certifying their products. Most recently, a Linux® distribution has become UNIX certified continuing the trend and value of basing operating systems on the UNIX standard. Download the UNIX Evolution Infographic to get more information.

UNIX: Driving Innovation Today

The UNIX OS plays a big role in the current market landscape and is an enabler of technologies such as cloud computing, security, virtualization, mobility, and more. It has a proven track record of adoption by Global 100 and Fortune 100 companies. The UNIX OS is a strong choice for verticals such as telecommunications, manufacturing, pharmaceuticals, financial services, government, healthcare, defense, and more. For these end-user enterprises, procuring certified UNIX systems and software ensures the highest level of availability, scalability, and maintainability for those who want to focus on their business with confidence and peace of mind without the worry of disruption in their global IT environments.

Single UNIX Specification- “The Standard”

The Single UNIX Specification is the standard in which the core interfaces of a UNIX OS are measured. The UNIX standard includes a rich feature set, and its core volumes are simultaneously the IEEE Portable Operating System Interface (POSIX) standard and the ISO/IEC 9945 standard.  The specification encompasses the base operating system environment, networking services, windowing system services, and internationalization aspects and programming languages. The latest version of the certification standard is UNIX V7, aligned with the Single UNIX Specification Version 4, 2018 Edition. Read or download the Single UNIX Specification here.

UNIX Open Standards Development

The Open Group Governing Board UNIX Systems Work Group sets the strategy and influences the direction for the evolution of the Single UNIX Specification. The Work Group is comprised of The Open Group Platinum Members, all industry leaders each with a representative on The Open Group Governing Board.  A few examples of UNIX based operating systems are IBM® AIX®, HPE™ HP-UX®, Oracle® Solaris®, and Inspur® K-UX.

Certification of Conformance to the Standard

The Open Group grants licenses through the UNIX Certification Program. Suppliers are granted a license to use the UNIX trademark in connection with a product when:

  • The product has demonstrated passing the applicable certification test suites.
  • The supplier has formally agreed to the terms of the Certification Program.

An Open Brand Certificate is issued for each Registered Product that has been certified against the standard. An entry is made in the Directory of Registered Products, which can be found on The Open Group website at

Read details on the UNIX certification.