installing from iso on partition to another partition, avoiding all access to usb

[Dan Hitt <dan.hitt@gmail.com>]

The question has recently come up about how to install debian from an
iso file but not burn a disc.

So far, there have been a couple of suggestions to burn to a usb stick.

Just for reference, this is certainly possible (and on ubuntu, you can
make a bootable usb stick quite easily, all gui, and this is from
personal experience).

Now, i have a different, but related question, and i don't want to
hijack Harry P's thread, so here it is:

Suppose that i don't want to make a bootable usb stick, or burn a cd,
or burn a dvd.

Instead, i want to devote a small partition to the project: i would
like to ideally place just an iso image on the partition, but i guess
it could be larger, but no more than a few G.  I would like to then
install from the iso partition to a different, larger partition, on
the same disk.  So the target would not be the whole disk, but just
part of it.  The nature of the iso partition wouldn't matter too much
to me (although it would be super cool if it could be an iso in a
filesystem of some partition with a real os on it).

This is surely possible in principle, isn't it?

Has anybody actually done this?

And if so, what are the steps?

TIA for any info.

dan