Portability of shell scripts from other *nixes

[Warren Block]

On Wed, 25 Jan 2012, Doug Poland wrote:

> I'm trying port some shell scripts to FreeBSD that were originally
> written on Darwin (OS X).
>
> The issue I'm having is the shebang line of the scripts in OS X is
> #!/bin/sh, and it turns out that is really an instance of bash, and
> the code contains some bashisms.  On FreeBSD I have bash in
> /usr/local/bin/bash.
>
> Is there an "easy/best" way to have a single shebang that works on
> both OS's?  I'd rather not change FreeBSD's bourne shell to bash with
> any symlinking of /usr/local/bin/bash to /bin/sh.

Turns out that causes mysterious problems:
http://forums.freebsd.org/showthread.php?t=29088