Hello, Jam documentation mentions that "Jam picks up variable settings from your environment by default". However, I could not find any documentation on what environment variables affect what options. In particular, I am looking for a way to pass on to Jam the --layout and --build-type options via environment variables. Currently I am building a boost rpm for local distribution by using the following command sequence in the rpm .spec file: %build ./configure --prefix=%{_prefix} --libdir=%{_libdir} cat Makefile | sed -e 's/BJAM_CONFIG=/BJAM_CONFIG=--layout=system --build-type=complete/' > Makefile.new mv Makefile.new Makefile make all If I understand correctly, I should be able to define the compile options via environment variables instead of resorting to a hack like above. I'd appreciate any pointers to more detailed documentation on how to accomplish the above with environment variables alone. Thank you in advance, --> Mika Heiskanen / FMI