Microsoft Windows Services for UNIX (SFU) is a software package produced by Microsoft which provides a Unix subsystem and other parts of a full Unix environment on Windows NT and its successors. The subsystem included is called Interix.
Like the Microsoft POSIX subsystem in Windows NT, Interix is not an emulation of a Unix kernel, but rather an implementation of a user-mode subsystem running directly on top of the Windows NT kernel.
It is important to note that though both Cygwin (a free alternative to Interix) and Windows Services for Unix provide header files and libraries that make it easier to recompile or port Unix applications for use on Windows, they do not make Unix binaries compatible with Windows binaries.
The current version of SFU contains:
SFU does not contain the following (but binaries are available for a separate installation[1]):
Although X Window System client libraries and applications are provided, SFU does not contain a native X server. Any of the numerous third-party Windows X servers can be used. Fully featured free alternatives include Cygwin/X, Xming, WeirdMind and WeirdX.
There was at least one beta release of the initial version of SFU before its final release in February 1999. This release was only in English and was supported on Windows NT 4.0 SP3+ for x86 and Alpha platforms. This is the only known release to support Alpha. It included a demonstration version of the MKS Toolkit along with the following components:
This second installment of SFU was released April 2000 and was also for English, however it was accompanied by a Japanese language release just two months later in June 2000. Both were supported on Windows NT 4.0 SP4+ and Windows 2000 on x86 platforms with Internet Explorer 4.01+. It supported the following UNIX versions: Solaris 2.6+, HP-UX 10.2+, AIX 4.2+, Tru64 UNIX 5.0+, and Red Hat Linux 5.1+. It included the following components:
This version was released May 2002 and was the first release to include the Interix subsystem. Previously Microsoft had released Interix 2.2 (actually version 2.2.5) as a separate product around the same time frame as SFU 2.0. For some reason the Interix version number jumped to 7.0 but this is still referred to as Interix 3.0 due to its release being 3.0. This was also released in English and accompanied by a later release in Japanese in October 2002, adding internationalization support. Both supported Windows NT 4.0 SP6a+, Windows 2000, and Windows XP Professional on x86 platforms with Internet Explorer 5.0+. The MKS Toolkit was no longer included. It included the following components:
This was the final release of SFU and the only release to be distributed free of charge. It was released January 2004 and included both English and Japanese versions for Windows 2000, Windows XP Professional, and Windows Server 2003 on x86 platforms with Internet Explorer 5.0+. It included Interix subsystem version 8.0 (release 3.5) adding internationalization support (at least for the English version which did not have such until now) and POSIX threading. This release could only be installed to an NTFS file system (earlier versions supported FAT; this was probably for new features in Interix 8.0). The following UNIX versions were supported: Solaris 7 and 8, Red Hat Linux 8.0, AIX 5L 5.2, and HP-UX 11i. It included the following components:
Windows Server 2003 R2 contains most SFU components, namely Microsoft Services for Network File System (NFS), Subsystem for UNIX-based Applications (aka Interix), and Identity Management for UNIX.[2]
Windows Vista Enterprise and Ultimate Editions also contain the Services for Unix components, now called the Subsystem for UNIX-based applications (SUA), and Client for NFS v3. The utilities and SDK are required to be downloaded separately. However, the server components from the SFU product line (namely Server for NFS, User Name Mapping, Server for NIS, Password Synchronization etc) are not included. [3]
Microsoft does not intend to produce any further standalone versions of the product. SFU will be available for download[4] until 2009; general support will continue until 2011; extended support until 2014[5].