About MSYS

MSYS is a collection GNU utilities such as bash, make, gawk and grep to allow building of applications and programs which depend on traditionally UNIX tools to be present. It is intended to supplement MinGW and the deficiencies of the cmd shell.

An example would be building a library that uses the autotools build system. Users will typically run "./configure" then "make" to build it. The configure shell script requires a shell script interpreter which is not present on Windows systems, but provided by MSYS.

A common misunderstanding is MSYS is "UNIX on Windows", MSYS by itself does not contain a compiler or a C library, therefore does not give the ability to magically port UNIX programs over to Windows nor does it provide any UNIX specific functionality like case-sensitive filenames. Users looking for such functionality should look to Cygwin or Microsoft's Interix instead.

Building for MSYS

To build an application for MSYS, users will need to install msysDVLPR.tar.gz. It contains the headers and libraries to for MSYS along with an old version of GCC and Binutils. Resulting programs will only run under MSYS.

MinGW build VS MSYS build

Some programs when used under the MSYS shell can be tricky. One such example is sed.

$ ls *.txt -1 | sed -e s/.exe/\&\!/g

Normally, sed will append "!" to the end of every .txt file, but if sed was compiled and link using MinGW, MSYS will treat it as a native application and will try to change "/" to "\" to compensate for the difference between UNIX path and WIN32, resulting in unpredictability when used under the MSYS shell.