Re: Default PATH for executing external programs

[Philip Nienhuis]

John W. Eaton wrote:
> On 11/07/2014 06:31 AM, Philip Nienhuis wrote:
>
> > First off, I think the whole issue is primarily a Windows one. I have
> > never
> > encountered it on my Linux systems.
>
> It is a problem if you have multiple versions of Octave installed and at
> least one version is in your PATH.  Then if you execute one of the
> others (not first in the PATH) the pkg command will execute Make and any
> package Makefile that uses "mkoctfile" will get the mkoctfile that
> corresponds to the copy of Octave that is first in the PATH instead of
> the one that corresponds to the one currently running.  That will cause
> trouble because mkoctfile has things like the location of Octave header
> files and libraries embedded in it.  Those things are obviously specific
> to a particular version.

Thank you for this explanation.
As I understand I've just been lucky; the situation you describe is what 
I have on my Linux systems. It must have worked because the Octave 
libraries for my installed versions probably didn't differ that much.

Another thing here is that binary parts of OF packages installed in 
different Octave versions end up in one and the same tree under 
...local/lib/packages, contrary to the .oct files from Octave itself; 
similar to the .m-file parts.
What I found is that I can use OF packages built with Octave-3.9.0+ 
without any problems with Octave-4.1.0+ [*] and some vice-versa; but not 
with Octave-3.8.2. So I think it may be needed to separate the binary 
parts of OF packages as well according to Octave version - if one wants 
different Octave versions peacefully co-installed.

Philip

[*] Several OF packages (incl. some in mxe-octave) can't be built 
anymore in 4.1.0+ as they depend on deprecated octave-map. But they can 
still be built in 3.9.0+ and then run fine in 4.1.0+.
I regularly build combined 3.9.0+/4.1.0+ mxe versions for MingW, more or 
less following patch #8469