Ruby sqlite3 gem not found - ruby-on-rails

Question

I recently downloaded Crunchbang and am downloading a Ruby program. I installed Ruby:
apt-get install ruby
apt-get install rubygems
apt-get install sqlite3
When I run the file, I get:
root#crunchbang:/Pentest/NTLMRelay/ZackAttack# ruby zackattack.rb
/usr/lib/ruby/1.9.1/rubygems/dependency.rb:247:in `to_specs': Could not find sqlite3 (= 1.3.6) amongst [] (Gem::LoadError)
from /usr/lib/ruby/1.9.1/rubygems/dependency.rb:256:in `to_spec'
from /usr/lib/ruby/1.9.1/rubygems.rb:1231:in `gem'
from /Pentest/NTLMRelay/ZackAttack/lib/zfdb.rb:7:in `<top (required)>'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from /Pentest/NTLMRelay/ZackAttack/clients/ews.rb:9:in `<top (required)>'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from /Pentest/NTLMRelay/ZackAttack/lib/zfclient.rb:6:in `<top (required)>'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from /Pentest/NTLMRelay/ZackAttack/lib/zfhttpd.rb:7:in `<top (required)>'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
from zackattack.rb:8:in `<main>'
I am completely at a loss. Help is appreciated/

Answer 1

You need to install ruby gem as well:
gem install sqlite3
If your program has a Gemfile, do:
gem install bundler
bundle install
Another advise, install ruby via RVM, it will save you from a number of headaches.
UPDATE:
Most likely you will also need the following package:
sudo apt-get install libsqlite3-ruby

Answer 2

You can also install the gem as follows using apt:
apt-get install ruby-sqlite3
or in my case:
apt-get install sqlite3-ruby

Answer 3

I would avoid installing Ruby using apt-get because you'll face a lot of problems (versions, gem management, etc) down the road. Use RVM instead.
Remove your apt-get installations (especially if your ruby -v returns something before 1.9) and then follow the instructions at http://rvm.io/rvm/install
RVM will allow you to install multiple Ruby versions and manage your gems more easily.
Once you're done with the rvm installation, do the following:
gem install sqlite3 -v 1.3.6
Once you have RVM running, things should become easier... Don't worry about the extra time you're spending in the beginning, it'll pay off :-)