Re: make not expanding variables

[Philip Guenther]

Take 3!  #(*$&(#*%$&


On Fri, Aug 8, 2014 at 8:55 PM, Philip Guenther <address@hidden> wrote:

> On Fri, Aug 8, 2014 at 7:43 AM, Vance Turnewitsch <address@hidden
> > wrote:
>>
>> I'm using Ubuntu 12.04 64bit with make version 3.81-8.1ubuntu1.1 and was
>> failing to build bitbake recipes. I narrowed it down to an odd problem
>> with
>> make not expanding variables. I've attached a sample make file (makefile)
>> with the "problem."
>>
>> When I use this makefile, I get a directory "{hi,hi2}" within TestMake but
>> instead there should be two directories within TestMake created: "hi" and
>> "hi2", correct?
>>
>
>
> Well, that depends on the behavior of the shell that your system's 'make'
> is compiled to use by default as ${SHELL}.
>

There are basically two possible explanations:
1) your system's 'make' doesn't think that it needs to invoke a shell at
all and is just exec'ing cp directly, OR
2) the ${SHELL} that your system's 'make' defaults to doesn't perform brace
expansion.

You can figure out what ${SHELL} is used by putting that in a rule; you can
then test *that* program to see if it does brace expansion.  If it
*doesn't*, then you've confirmed the answer is (2).  If it *does*, then
perhaps strace make to confirm whether it's exec'ing the shell or cp
directly.


HOWEVER, you should note that "brace expansion" is not part of the
POSIX/Single-Unix specification, so a Makefile using it is not portable and
you should consider doing the expansion yourself.  The examples you gave
are trivially expanded (indeed, shorter and easier to type *without* the
braces); in the more complicated cases some careful use of variables should
be considered...


Philip Guenther