Request: Posix compatibility when called sh

[GregDavidson]

Dune could almost replace bash and zsh. Yet bash and zsh have one key advantage: they emulate a Posix-compliant Bourne Shell when they're called via a link named sh and can therefore be installed as the System Shell. Only a System Shell can absorb extensions at login time and propagate them to all processes in a login session via the environment. (Note: dash strips the environment of extensions and is therefore unsuitable.)

Please consider adding such a feature to Dune and make it the first modern shell which can obsolete these ancient monstrosities!