Re: How to change certain rules such that they will not executed as long as the target is available?

[couling]

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
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-make
> 
> 

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