CMAKE_SYSTEM_NAME

The name of the operating system for which CMake is to build. See the CMAKE_SYSTEM_VERSION variable for the OS version.

Note that CMAKE_SYSTEM_NAME is not set to anything by default when running in script mode, since it's not building anything.

System Name for Host Builds

CMAKE_SYSTEM_NAME is by default set to the same value as the CMAKE_HOST_SYSTEM_NAME variable so that the build targets the host system.

System Name for Cross Compiling

CMAKE_SYSTEM_NAME may be set explicitly when first configuring a new build tree in order to enable cross compiling. In this case the CMAKE_SYSTEM_VERSION variable must also be set explicitly.