gistfile1.sh

$ tar xvzf rubygems-1.3.1.tar.gz
$ cd rubygems-1.3.1/
$ sudo ruby setup.rb 
./lib/rubygems/gem_path_searcher.rb:96:in `lib_dirs_for': undefined method `join' for nil:NilClass (NoMethodError)
   from ./lib/rubygems/gem_path_searcher.rb:26:in `initialize'
   from ./lib/rubygems/gem_path_searcher.rb:25:in `each'
   from ./lib/rubygems/gem_path_searcher.rb:25:in `initialize'
   from ./lib/rubygems.rb:684:in `new'
   from ./lib/rubygems.rb:684:in `searcher'
   from ./lib/rubygems.rb:683:in `synchronize'
   from ./lib/rubygems.rb:683:in `searcher'
   from ./lib/rubygems/custom_require.rb:34:in `require'
   from /opt/local/lib/ruby/1.8/tmpdir.rb:14
   from ./lib/rubygems/custom_require.rb:31:in `gem_original_require'
   from ./lib/rubygems/custom_require.rb:31:in `require'