CMAKE_HOST_SYSTEM ----------------- Composit Name of OS CMake is being run on. This variable is the composite of :variable:`CMAKE_HOST_SYSTEM_NAME` and :variable:`CMAKE_HOST_SYSTEM_VERSION`, e.g. ``${CMAKE_HOST_SYSTEM_NAME}-${CMAKE_HOST_SYSTEM_VERSION}``. If :variable:`CMAKE_HOST_SYSTEM_VERSION` is not set, then this variable is the same as :variable:`CMAKE_HOST_SYSTEM_NAME`.