> 
> It depends on what you want to do after copying the content of ENV.
> If you want to remove all environment variables, copying will not
> work.  To clear environment variables, try "ENV.delete_if{true}".
> 
> "clear" is not supported by ENV, just because I considered removing
> all environment variables might not be intentional.
> 
> 							matz.

Right.

In fact, I am trying to make use of ENV to implement a clone program
of the UNIX env, http://figaro.ddns.comp.nus.edu.sg/~zhoujing/codes.html
.. When implementing the -i option, I need to remove all environment
variables.