Re: [LUG] Makefiles

[Benjamin A'Lee <bma+lists@xxxxxxxxxxxxxx>]

On Thu, Nov 08, 2007 at 01:15:54PM +0000, Robin Cornelius wrote:
> Arrg, having another braindead day
> 
> How can i do a conditional make file as such :-
> 
> distclean:
> if [ -f Makefile.qmake ]
>       ${MAKE} -f Makefile.qmake distclean
>       rm -f Makefile
> endif
> 
> I'm trying to use a GNU makefile to bootstrap a qmake process but if
> someone runs distclean twice or on a fresh install it creates a fatal
> make error. I've found a number of examples on google but none seem to
> actually work.

You can make make ignore errors in a rule by prepending a '-':

        distclean:
                -${MAKE} -f Makefile.qmake distclean
                -rm -f Makefile

Alternatively, you can embed the shell command:

        distclean:
                if [ -f Makefile.qmake ]; \
                        ${MAKE} -f Makefile.qmake distclean; \
                        rm -f Makefile; \
                fi

Note that you need to escape the shell code for this to work. To escape
a variable, so that it's parsed by the shell instead of by make, prepend
an extra '$'.

If you were using BSD make, you could use a conditional:

        distclean:
        .if exists(Makefile.qmake)
                ${MAKE} -f Makefile.qmake distclean
                rm -f Makefile
        .endif

Unfortunately, GNU make can't do this, AFAIK.


-- 
Benjamin A'Lee :: benjamin.alee@xxxxxxxxxxxxxx
Subvert Technologies :: http://subvert.org.uk/

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