Re: shell <something>: non-POSIX variable name

[Ralf Wildenhues]

Hi Axel,

* Axel Thimm wrote on Fri, May 05, 2006 at 02:16:50PM CEST:
> 
> autoconf -Wall doesn't like $(shell xxx) constructs becuase they are
> non-portable.

Yes.  It outputs a warning to this extent (but finishes successfully).

> Is there a portable way to achieve $(shell xxx) functionality or
> failing that to indicate to automake that this projects requires make
> with GNU extensions?

In some cases $(shell xxx) may be replaced by other means, for example a
substituted variable computed at configure time, or an Automake
conditional, or similar.  But that depends on the specific usage, and
won't give you the full flexibility of $(shell ..).

I don't know of a way to tell Automake "we require GNU make".  The
manual warns against using those constructs because some of them are
misunderstood by Automake, causing weird errors.  If you only need them
for stuff rather unrelated to the stuff that is done by the
Automake-created part of the Makefile, you may be able to separate it
into a GNUmakefile file, and include Makefile from there;
  info Automake "Third-Party Makefiles"

has some more information about this (even if the main topic of that
node is a different one).

Cheers,
Ralf