With Cygwin [ sɪɡwɪn ] can be programs that usually run on POSIX systems such as GNU / Linux, BSD and Unix, ported to Microsoft Windows. There is a compatibility layer that provides the Unix API for different versions of Microsoft Windows are available, on the basis of a variety of programs from the Unix world under Microsoft Windows can be translated.

Using Cygwin ported programs running under Windows NT, Windows 2000, Windows XP, Windows Vista, Windows Server 2003, and since version 1.7 under Windows 7 and Windows Server 2008. Reportedly for successful operation under Windows 8 manual correction of the configuration is required. In older versions, programs run under Windows 9x.

Cygwin was originally programmed by the company Cygnus Solutions and since its acquisition by the software company Red Hat is done there, the further development.


Core of Cygwin is the so-called Cygwin DLL ( cygwin1.dll ), a dynamic link library that provides Unix APIs. The APIs of the Cygwin DLL form the counterpart to the system calls on Unix. The ported to Cygwin programs are usually not be run standalone, as they are linked against the Cygwin DLL and thus are dependent on this.


There is Cygwin / X also a port of the X.Org server on the Cygwin environment so that standing by a complete X server on Microsoft Windows.

In the program package Cygwin / X Cygwin is included.

By ported X server, it is possible either UNIX / Linux programs that have been compiled for Windows, locally run on the Windows machine ( Running startxwin.bat ), or programs that run on a Unix or Linux computer be present on Windows; also you can, starting from the Windows machine on which Unix computer log in ( Running startxdmcp.bat ).

This can be useful for home users and programmers, the Windows and Unix / Linux running simultaneously.

Local partitions are referred to as / cygdrive / c, / cygdrive / d etc.. On Windows shares can be accessed with / / host / share / file.

A SSH server is possible through Cygwin, which can be installed on Windows as a service. Frequently Cygwin is also used to program bash procedures that can then fulfill automated system functions. These include local or remote (remote) backups ( backups ) on other Unix systems. A similar functionality to Cygwin realized now Microsoft's Services for Unix package (SFU ), which is based on the Interix system. Microsoft Windows Services for UNIX ( SFU ) has been renamed as part of the Vista introduction to the "Subsystem for UNIX -based Applications" (SUA ) and is included in the editions "Enterprise " and " Ultimate" of Vista.


Cygwin began in 1995 as a project by Steve Chamberlain, a Cygnus developers. He noticed that had on PCs with Intel x86 CPUs, Windows NT and Windows 95 operating system, was usually used as a COFF object file format. In addition, he had noticed that the GNU compiler ( GCC) already offered support for x86 and COFF in connection with the C library newlib. So it should, so his conclusion - at least in theory - not be too difficult, the GCC refocus in order to create another cross-compiler, which then generates executable directly executable files for the Windows platform. In practice, the task was associated with a certain application, the Chamberlain finally successfully mastered, so that first sample programs could be generated and tested.

Next, the compiler itself should also be made ​​to run on a Windows system; first had to be made to run on the Windows system in an emulation some basic components of the usual GNU command line configuration, various shell scripts, as well as the bash shell itself. The Win32 API of Windows already contained numerous very similar functionality so the majority of system calls used had to be adjusted only. This led to various Cygwin libraries called DLLs that touched down directly on the Windows system, but upwards the typical Unix services ( APIs) offered.

By 1996 there were some other developers who joined the project, especially because it was becoming clear that it might be worthwhile to offer Unix applications using the Cygwin components for Windows systems. (Previous Unix -to- Windows porting based mostly on the DJGPP development environment ). Approximately 1998 Cygnus began to market Cygwin profitably. Meanwhile Cygwin is available as free software under the GPL and also has further developed under the auspices of Red.