From: why the lucky stiff <ruby-talk@...>
Date: 2004-05-10T15:50:04+09:00
Subject: Re: running gem

Chad Fowler wrote:
> We us a program called "env" with the argument "ruby" to
> find ruby in the path and run the script with whatever ruby was found
> in the path.

In the classic install.rb, the path to ruby is used rather than 'env'. 
This is great for situations where ruby isn't anywhere that can be found 
by 'whereis' or 'env'.  The path is built like so:

   require 'rbconfig'
   c = ::Config::CONFIG
   rubypath = c['bindir'] + '/' + c['ruby_install_name']

I like this approach a lot.  This way, if I want to install RubyGems for 
my Ruby 1.6 installation, then `ruby16 install.rb' will do the trick fine.

_why