= Cygwin =
What Is Cygwin? 编辑
Cygwin is a Linux-like environment for Windows. It consists of two parts：
- A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing substantial Linux API functionality.
- A collection of tools, which provide Linux look and feel.
The Cygwin DLL works with all non-beta, non "release candidate", ix86 32 bit versions of Windows since Windows 95, with the exception of Windows CE. 
What Isn't Cygwin? 编辑
- Cygwin is not a way to run native linux apps on Windows. You have to rebuild your application from source if you want to get it running on Windows.
- Cygwin is not a way to magically make native Windows apps aware of UNIX ® functionality, like signals, ptys, etc. Again, you need to build your apps from source if you want to take advantage of Cygwin functionality.
What's New and How Do I Get it? 编辑
The latest net releases of the Cygwin DLL are numbered 1.n.x, where "n" is currently "5" (e.g., 1.5.18). Any cygwin program built from December 1998 onward should work correctly with 1.n.x DLLs.
The 1.n.x version numbering refers only to the Cygwin DLL. Individual packages like bash, gcc, less, etc. are released independently of the DLL. The setup.exe utility tracks the versions of all installed components and provides the mechanism for installing or updating everything available from this site for Cygwin.
Run setup.exe any time you want to update or install a cygwin package.
Note that, when installing packages for the first time,h setup.exe does not select everything by default. Only the minimal base packages from the cygwin distribution are installed by default.
When running setup.exe, clicking on categories and packages in the package installation screen will provide you with the ability to control what is installed or updated.
Clicking on the "Default" field next to the "All" category will provide you with the opportunity to install every Cygwin package. Be advised that this will download and install hundreds of megabytes to your computer. The best plan is probably to click on individual categories and install either entire categories or packages from the categories themselves.
Once you've installed your desired subset of the Cygwin distribution, setup.exe will remember what you selected so rerunning the program will update your system with any new package releases.