CMAKE_HOST_SYSTEM_VERSION

The OS version CMake is running on.

A numeric version string for the system. On systems that support uname, this variable is set to the output of uname -r. On other systems this is set to major-minor version numbers.

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© 2000–2011 Insight Software Consortium
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.5/variable/CMAKE_HOST_SYSTEM_VERSION.html