FYI, I hope to be able to commit something to the tree RSN which
will support this, and doesn't require union mounts, so that Solaris,
Darwin and Linux users won't lose out. (Darwin seems to lack an
/sbin/mount_union command, although it's cross-referenced from
mount(8). I think Apple should hire the wonderful Thomas Klausner,
who has made such a difference to the NetBSD manual pages).

Regards,
Alistair

On Wed, Oct 31, 2001 at 10:18:22AM +0900, sen_ml@eccosys.com wrote:
> I'm wondering if there is some good mechanism to test multiple
> versions of the same software on the same machine.  For example, I'd
> like to be able to test both Emacs 20.7 and Emacs 21.1 on the same
> machine.  Further, it would be nice not to have to modify any of the
> packages just to be able to do this -- i.e. it'd be nice to have a
> general mechanism, not one that's specific to a particular package in
> pkgsrc.
> 
> After some thinking, it occurred to me that I might be able to prepare
> a "base" of packages (ones that don't need to have multiple versions
> tested) in /usr/pkg, and then create a separate union mount for each
> version of a piece of software I wanted to test.  For example, I'd
> perform one union mount to test Emacs 20.7, and I'd unmount that and
> union mount something separate when testing Emacs 21.1.
> 
> One obvious problem with this is the content of /var/db/pkg.  I
> suppose I could also do union mounting for /var/db/pkg, but that seems
> error-prone.  Another idea might be to make /var/db/pkg a symbolic
> link pointing to some place under /usr/pkg (/usr/pkg/pkg?).  Better
> ideas welcome!
> 
> There may well be other problems I haven't thought of too ;-)
> 
> Does anyone have a better general approach?  If something like this
> is documented somewhere already, please let me know where that is.
> 
> Any feedback would be much appreciated.