1SUBDIRS = s00 s01 s02 s03 s04 s05 s06 s07 s08 s09 s10 2 3all: $(SUBDIRS) 4 5clean: 6 for d in $(SUBDIRS); do cd $$d && make clean && cd ..; done 7 8$(SUBDIRS): 9 cd $@ && make 10 11.PHONY: all clean $(SUBDIRS) 12