Hi,

At Mon, 31 Jul 2006 22:57:03 +0900,
Curt Hibbs wrote in [ruby-talk:205183]:
> > Win32 API GetEnvirionmentVariable() doesn't tell if the
> > variable is empty or unset.  Actually, there is no way to set
> > an empty environment variable by cmd.exe.  I'm not sure if it
> > is misfeature or restriction by design.
> 
> As far as I know, Windows uses an empty env. var. as a signal to
> delete that env. var.

In accurate, Windows allows an empty env var, but cmd.exe (and
of course, command.com) uses it to delete it.

  $ ./ruby -e 'ENV["FOO"]="";p system("cmd /c set FOO")'
  FOO=
  true

And, usa has fixed the empty value issue today.

-- 
Nobu Nakada