From duncan@research.bell-labs.com  Thu Jan 14 00:56:06 1999
From: duncan@research.bell-labs.com (Duncan Temple Lang)
Date: Wed, 13 Jan 1999 19:56:06 -0500
Subject: make docs
Message-ID: <199901140057.BAA25116@hypatia.math.ethz.ch>


The following should do what you want (assuming I understand the problem)

 ifndef PADI_HOME
   PADI_HOME=$(shell pwd)
   # or PADI_HOME=${PWD}
 endif

GNU make even allows you determine the source of the value of the
variable - environment, command line, automatic variable, etc.
via the origin function

ifeq "$(orgin PADI_HOME)" "environment"
  # do something.
endif


I can't remember if Gmake guarantees that the 
execution of the shell will give a Bourne shell.
I presume it will use the current value of SHELL
and so the following
     PADI_HOME=$(shell ${PADI_HOME-$PWD})
may not be as robust as the internal gmake solutions.



Duncan


> Cc: R-devel <stat.math.ethz.ch!R-devel>
> References: <99Jan13.151923est.13454@mailgate.bank-banque-canada.ca>
> From: Peter Dalgaard BSA <biostat.ku.dk!p.dalgaard>
> Date: 13 Jan 1999 22:44:50 +0100
> Lines: 23
> Sender: stat.math.ethz.ch!owner-r-devel
> Precedence: bulk
> 
> Paul Gilbert <pgilbert@bank-banque-canada.ca> writes:
> 
> > How quickly I forget. Thanks everyone for reminding me about gnu make. I had to
> > switch back because
> > 
> > PADI_HOME:sh = if [ $PADI_HOME ] ; then echo $PADI_HOME; else echo $PWD ; fi
> > 
> > works to conditionally set a variable in Sun make but not in gnu. Does anyone
> > know how to do an equivalent thing in gnu make?
> 
> PADI_HOME=$(shell if [ ....)
> 
> or something like that. 
> 
> I suspect, by the way, that the whole thing might be better written as 
> 
> PADI_HOME=$(shell ${PADI_HOME-$PWD})
> 
> -- 
>    O__  ---- Peter Dalgaard             Blegdamsvej 3  
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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-- 
_______________________________________________________________

Duncan Temple Lang                duncan@research.bell-labs.com
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make docs
Duncan Temple Lang