How to pass user defined parameters to rpmbuild to fill variables

Question

is it possible to pass parameters to rpmbuild to fill user defined variables that are called inside the spec file?

Example: The user defined variable %{foobar} which is called in the .spec file (but empty) should be filled with the variable which is passed when executing the rpmbuild command

rpmbuild -bb --foobar="Foo" somespecfile.spec 

Answer 1

rpmbuild -bb --define '_foobar Foo' somespecfile.spec 

and refer it within the spec as %{_foobar}

(the _ is a convention, not a must)

Answer 2

The closest you can get AFAIK are conditional builds, which allow you to do things like

rpmbuild -ba newpackage.spec --with feature 

see http://rpm.org/user_doc/conditional_builds.html .