使用make -nd调试makefile以及如何直接使用shell命令

可以使用make -nd调试makefile
yes := $(shell echo 'bbbbbbb')
.PHONY: none

none:
    $(warning 1111111111111111111)
    $(info 2222222222222222222)
    @echo 123 | sed -e 's/1/aaaaaaa/'
    @echo $(yes)
clean:
    @for dir in $(dirs_to_clean) ; do \
        echo "Cleaning $$dir..."; \
        rm -rf $$dir; \
    done
    @echo "Clean."; \

nosd:
    @echo xxxxxxxxxxxxx

javac_version := $(shell javac -version 2>&1 | head -n 1 | grep '[ "]1\.[56][\. "$$]')
ifeq ($(strip $(javac_version)),)
$(info Your version is: $(shell javac -version 2>&1 | head -n 1).)
endif