A UNIX-like POSIX environment for Microsoft Windows OS's. See http://www.cygwin.com/ The CYGWIN project was started by CYGNUS Inc. who was purchased by Red Hat in 2000. CYGWIN features a bash shell and the software distrubution includes nearly all of the most common GNU shell utilities. The utilities have been ported to run in the win32 environment on top of the cygwin1.dll POSIX emulation layer. See also the handy free X-Windows Server at http://xfree86.cygwin.com/