Makefile

Hi:

Here is something I don't know,who can explain it to me? Thank you!!

%.d: %.c

$(SHELL) -ec &#39;$(CC) $(DEPFLAGS) $(CFLAGS) -c $< | sed &#39;\&#39;&#39;s/\($*\)\.o[ :]*/\1.o $@ : /g&#39;\&#39;&#39; >$@; [ -s $@ ] || rm -f $@&#39;

FORCE: ;

what is it function?