all: all.dirs
install: install.dirs
clean: clean.dirs clean.var
distclean: distclean.dirs distclean.var

ifneq ($(SUBDIRS),)
all.dirs:
	set -e; for dir in $(SUBDIRS); do make -C $$dir all; done
install.dirs:
	set -e; for dir in $(SUBDIRS); do make -C $$dir install; done
clean.dirs:
	set -e; for dir in $(SUBDIRS); do make -C $$dir clean; done
	rm -f *.done
distclean.dirs:
	set -e; for dir in $(SUBDIRS); do make -C $$dir distclean; done

else

all.dirs:
install.dirs:
clean.dirs:
distclean.dirs:

endif

clean.var:
	rm -rf $(CLEAN)
distclean.var:
	rm -rf $(DISTCLEAN)