Microsoft POSIX subsystem

The POSIX subsystem is next to the Win32 and OS/2-Subsystem one of three subsystems that were provided in Windows NT. It supports POSIX - compatible programs, and is represented by the service file psxss.exe.

Windows NT implemented the POSIX subsystem mainly to obtain orders from the U.S. government, as they demanded 151-2 POSIX compatibility in the Federal Information Processing Standard. Implements this is only the first version of POSIX.1 - this raises a number of limitations, so POSIX programs are about neither network nor graphics capability in Windows NT.

Although it has never been updated since its initial implementation in 1993, the POSIX subsystem was received until Windows 2000 and was removed only with Windows XP or Windows Server 2003. As a replacement Microsoft developed the Microsoft Windows Services for UNIX.

References and sources

• Windows operating system component
• POSIX