CMAKE_INSTALL_PREFIX environment variable - doesn't work?

CMAKE_INSTALL_PREFIX has to be set as a CMake variable:

cmake -DCMAKE_INSTALL_PREFIX:PATH=/path/to/installation/directory ..

But CMake also supports using the DESTDIR environment variable:

export DESTDIR=/path/to/installation/directory
make install

CMAKE_INSTALL_PREFIX is a CMake variable, not an environment variable. It can be set with cmake -DCMAKE_INSTALL_PREFIX=yourpath