Interix

Interix was an optional, POSIX-conformant Unix subsystem for Windows NT operating systems. Interix was a component of Windows Services for UNIX, and a superset of the Microsoft POSIX subsystem. Like the POSIX subsystem, Interix was an environment subsystem for the NT kernel. It included numerous open source utility software programs and libraries. Interix was originally developed and sold as OpenNT until purchased by Microsoft in 1999.
Interix versions 5.2 and 6.0 were respective components of Microsoft Windows Server 2003 R2, Windows Vista Enterprise, Windows Vista Ultimate, and Windows Server 2008 as Subsystem for Unix-based Applications (SUA). Version 6.1 was included in Windows 7 (Enterprise and Ultimate editions) but disabled by default, and in Windows Server 2008 R2 (all editions).
It was available as a deprecated separate download for Windows 8 and Windows Server 2012, and is not available at all on Windows 10.
Details.
The complete installation of Interix included (at version 3.5):
The development environment included support for C, C++ and Fortran. Threading was supported using the Pthreads model.
Additional languages could be obtained (Python, Ruby, Tcl, etc.). Unix-based software packaging and build tools were available for installing or creating pre-build software packages.
Starting with release 5.2 (Server 2003/R2) the following capabilities were added:
With release 6.0 (Vista and Server 2008) the following new features were added:
Interix release 6.0 for Vista was only available with the Ultimate and Enterprise editions.
Interix release 6.1 was available for Windows Server 2008 R2 and Windows 7 for the Enterprise and Ultimate editions.
Support.
Traditional support was provided by Microsoft for a fee or service contract, though released hotfixes can usually be obtained free of charge from Microsoft. Previously, free support could be found via the forums at the SUA Community site and with the FAQ, however this appears to have been withdrawn.
Additions.
Additional pre-built applications and development libraries could be obtained for free from the SUA Community site, the Gentoo-prefix site and the Debian-Interix site. These included commonly used applications not part of the Microsoft installation such as OpenSSH, Git, Python and bash.
The SUA Community site included for developers of Interix and the site has been contracted by Microsoft for several Interix and SUA updates of utilities and documentation.
History.
This product began to be developed in 1996 under the product name OpenNT by Softway Systems, Inc. before the name was changed to Interix in 1998. The last release by Softway Systems was release 2.2. Softway Systems had virtually completed the next release code-named Firebrand in 1999 which became the basis of Interix 3.0.
The Interix interoperability suite developed by Softway Systems Inc., included substantial code from OpenBSD. Microsoft acquired Interix in 1999.
Microsoft continued to distribute Interix 2.2 as a standalone product until 2002.
Interix release 3.0 was released as component of Windows Services for Unix (SFU) 3.0 in 2002. Interix release 3.5 was released as component of SFU 3.5 in January, 2004.
Interix became integrated as a component of the regular Windows OS distribution as a component of Windows Server 2003 R2 in December, 2005 at release 5.2 and was a component of the Windows Vista release as release 6.0 (RTM November, 2006). Windows Server 2008 had release 6.0. Windows 7 and Windows Server 2008 R2 included SUA 6.1.
Microsoft announced in 2011 that Interix would not be included in Windows versions after Windows 8 and customers should start migrating their applications to an alternative solution.