Someone

        rpmbuild -ba -vv "$RPM_SPEC" \                                                                                                               
                --define "_topdir $PACKAGE_DIR" \                                                                                                    
                --define "_sourcedir $PACKAGE_DIR" \                                                                                                 
                --define "_builddir $BUILD_DIR" \                                                                                                    
                --define "_rpmdir $BINARY_DIR" \                                                                                                     
                --define "_srcrpmdir $SOURCE_DIR" \                                                                                                  
                --define "buildroot $ROOT_DIR" \                                                                                                     
                --define "_build_name_fmt %%{NAME}-%%{VERSION}-%%{RELEASE}.%%{ARCH}.rpm" \                                                           
                --target="$ARCH"