Interix

Interix was an optional, POSIX-conformant Unix subsystem for Windows NT operating systems. Interix is a component of Windows Services for UNIX, and a superset of the Microsoft POSIX subsystem. Like the POSIX subsystem, Interix is an environment subsystem for the NT kernel. It includes numerous open source utility software programs and libraries. Interix was originally developed and sold as OpenNT until purchased by Microsoft in 1999.