How to go back to bash (from dash)?

[Ali Milis]

Magnus Therning wrote:

> >May I know, how to return to bash as  /bin/sh (from dash)?
> >Why it is not in /etc/alternatives?
>
> $ sudo dpkg-reconfigure dash
>
> Then you'll be asked if you want dash to be /bin/sh. Answer "no" and you
> revert to having bash as /bin/sh.

Thank you! May I know what was behind introducing POSIX's "dash"?
Many bash scripts break if using dash  B-(

And is there any specific reason not using /etc/alternatives?

regards,
--
  Ali Milis.