I Think what you're looking for is
http://www.gnu.org/software/make/manual/make.html#index-order_002donly-prerequisites-155
order-only-prerequisites . These act just like normal prerequisites except
that they will ignore the date.
To use them just put a pipe (|) after the normal prerequisites (there don't
have to be any) and everything that follows will be treated as an
order-only-prerequisite.
item : prereq | order-only-prereq
command
Hope this helps.
Peng Yu wrote:
>
> I have the following Makefile to extract tar files. However, it will
> always extract all the tar files. I could add touch $@ after tar xzvf
> $<. But I prefer not to do so. Because I don't want change the date of
> the extracted package.
>
> I'm wondering if there is any walkaround to not to update these rules
> as long as the targets exist.
>
> .PHONY: all
>
> TAR_GZ_FILES:=$(wildcard *.tar.gz)
> DIRS:=$(patsubst %.tar.gz,%,$(TAR_GZ_FILES))
>
> all: $(DIRS)
>
> $(DIRS): %: %.tar.gz
> tar xzvf $<
>
>
> --
> Regards,
> Peng
>
> _______________________________________________
> Help-make mailing list
> [email protected]
> http://lists.gnu.org/mailman/listinfo/help-make
>
>
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