CPACK_PACKAGING_INSTALL_PREFIX

The prefix used in the built package.

Each CPack generator has a default value (like /usr). This default value may be overwritten from the CMakeLists.txt or the cpack(1) command line by setting an alternative value. Example:

set(CPACK_PACKAGING_INSTALL_PREFIX "/opt")

This is not the same purpose as CMAKE_INSTALL_PREFIX which is used when installing from the build tree without building a package.