[Rd] What version is sh?

[Duncan Murdoch]

I'm trying to write an automatic check of the toolset installation for
R.  It'll get all the tools to print their version numbers, and
complain if they aren't acceptable ones.

However, I can't see how to get sh to print version information.  Is
there some way to do it?

The sh I'm worried about is the one that comes with Cygwin, if there
isn't a standard approach.

Duncan Murdoch