Re: How do I make a portable test??

[Dr. David Kirkby]

John Burger wrote:
> 
> > From: "Dr. David Kirkby" <address@hidden>
> 
> [Much elided]
> 
> > dnl something here generates an error:
> > dnl "test: ==: unexpected operator" on a Sun running NetBSD 1.6
> > if test $gsl_inc_count == 0 && test $gsl_lib_count == 0; then
> >    gsl_not_installed=1
> > elif test $gsl_inc_count != 2 || test $gsl_lib_count != 2; then
> >    gsl_incomplete=1
> > fi
> 
> I believe that the test operator = is more portable than ==.  If you're
> really after numeric equivalence, there's a -eq operator that I think
> is fairly portable.  For what it's worth, == is also unrecognized on
> Mac OS X, which has a BSD lineage as well.

Okay. Looks like the -eq might be my best bet then, as this is a
numeric rather than string comparision. 
 
> A separate thing I noticed: if your variable gsl_inc_count is empty or
> undefined, test won't see it - its first argument will be your
> (intended) operator.  For this reason, I always quote such variable
> arguments to test, if there's any chance they can be empty, e.g.,
> 
>    if test "$gsl_inc_count" = 0 && ...
> 
> Historically, the really retentive thing to do is something like:
> 
>    if test x"$gsl_inc_count" = x0 && ...
> 
> or, I suppose, for a numeric comparison this would work:
> 
>    if test 0"$gsl_inc_count" -eq 0 && ...
> 
> Usually, though, I can't bear to write such grotesqueries.

I'll try it with -eq and see if that works on all the systems I have
easy access to. I've got access to other systems on Sourceforge's
compile farm, but they are a bit more of a pain to use for me. Hence I
decided to set up my own mini compile-farm, to test for portability
issues like this. So far I have 3 Suns and a PC, all running different
operating systems. I'd like to get a Dec Alpha too, as their floating
point is quite fussy. 

-- 
Dr. David Kirkby,
Senior Research Fellow,
Department of Medical Physics,
University College London,
11-20 Capper St, London, WC1E 6JA.
Tel: 020 7679 6408 Fax: 020 7679 6269
Internal telephone: ext 46408
e-mail address@hidden