Re: $HOME/.. great for Android 8 and Termux

[積丹尼 Dan Jacobson]

E.g., we can only access /data/data/com.termux/*

https://developer.android.com/training/data-storage/app-specific

So as Termux sets HOME=/data/data/com.termux/files/home
we can use its $HOME as a keystone to access the rest of its tree.
(However other apps' internal directory structure will probably differ,
so we can't just assume $HOME/../bin, $HOME/../usr/tmp .)

Anyway, we have avoided hardwiring full paths by instead grabbing on to
items from the environment. So the user could first do
$ ssh machine env
to see what he could grab on to, to do something similar in his .emacs.