You forgot to require "rbconfig"

ruby -v -rrbconfig=20

> From: Hassan Schroeder <hassan.schroeder / gmail.com>
> Reply-To: <ruby-talk / ruby-lang.org>
> Date: Wed, 28 Jul 2010 08:22:42 +0900
> To: ruby-talk ML <ruby-talk / ruby-lang.org>
> Subject: Re: Which Ruby is in use?
>=20
> On Tue, Jul 27, 2010 at 3:52 PM, Joel VanderWerf
> <joelvanderwerf / gmail.com> wrote:
>=20
>>>>>> File.join *Config::CONFIG.values_at("bindir", "ruby_install_name")
>>>>=20
>>>> =3D> "/usr/local/bin/ruby"
>>>=20
>>> Works in a Rails console, but not a Ruby program. But thanks, now
>>> that I consider it I should be able to work with that =A0:-)
>>=20
>> Hm, that's surprising. I tested it in ruby and jruby programs. What's th=
e
>> problem?
>=20
> ripple:~$ cat foo.rb
> puts File.join *Config::CONFIG.values_at("bindir", "ruby_install_name")
> ripple:~$ ruby foo.rb
> foo.rb:1: uninitialized constant Config (NameError)
> ripple:~$ jruby foo.rb
> foo.rb:1: uninitialized constant Config (NameError)
> ripple:~$
>=20
> --=20
> Hassan Schroeder ------------------------ hassan.schroeder / gmail.com
> twitter: @hassan
>=20