checking command output

[Adam Mercer]

Hi

I while ago I posted to the libtool list [1,2] regarding a problem I
was having with a autotools based project and the condor workflow
management system [3]. With the help of Ralf and the Condor developers
a workaround, and more importantly a solution, was found. When
compiling code for use with condor the compiler needs to be prefaced
with a script called condor_compile which alters the behaviour of
certain things, and this script wasn't behaving as the autotools
expected, i.e. in trying to find which linker should be used:

$ condor_compile gcc -print-prog-name=ld
/opt/condor/lib/ld
ERROR: Internal ld was not invoked!
ERROR: Executable may not be linked properly for Condor!
ERROR: For users of Condor on Linux, we highly recommend
ERROR: using the default compiler that came with the
ERROR: distribution. Usually placing /usr/bin first in
ERROR: your path will remedy this error.
ERROR: To learn more about this error, visit this web page:
ERROR: http://www.cs.wisc.edu/condor/manual/faq.html
ERROR: and read the FAQ entry about this problem for your
ERROR: revision of Condor.
$ echo $?
1
$

this has now been fixed in condor and will be present in the next
release, i.e. the output is now

$ /path/to/fixed/condor_compile gcc -print-prog-name=ld
/opt/condor/lib/ld
$ echo $?
0
$

Currently I am working round this problem but when the fixed version
is released I no longer want to apply the workaround, therefore I
would like to add a check  to configure that determines if the
workaround is needed. At the moment I am using the version to do this,
i.e. I have been told by the developers that this will be fixed in
condor-7.4.2, for the stable series, and condor-7.5.1, for the
development series.

It seems to me that a better test would be check the output of
"condor_compile gcc -print-prog-path=ld" and act accordingly. I've
therefore been looking for a macro that gets the output from a given
command, but can't find anything. Does such a macro exist?

If not how could I achieve this?

Cheers

Adam

[1] http://lists.gnu.org/archive/html/libtool/2009-05/msg00023.html
[2] http://lists.gnu.org/archive/html/libtool/2009-11/msg00088.html
[3] http://www.cs.wisc.edu/condor/