The FindBoost.cmake module, which is used in this recipe, will try to locate the Boost libraries in standard system installation directories. Since we link to the imported Boost::filesystem target, CMake will automatically set the include directories and adjust the compile and link flags. In case the Boost libraries are installed in a non-standard location, one can pass the root of the Boost installation at configuration time using the BOOST_ROOT variable in order to point CMake to also search the non-standard path:
$ cmake -D BOOST_ROOT=/custom/boost/
Alternatively, one can pass both the BOOST_INCLUDEDIR and BOOST_LIBRARYDIR variables for the directories containing headers and libraries:
$ cmake -D BOOST_INCLUDEDIR=/custom/boost/include ...
