OSX Ruby Gems Add to ruby path?

Question

I am just starting to learn ruby. It seems that the default gems install path is not part of Ruby. Is this normal behavior? How can I set the default ruby path? Example:

[11:53:33]wuntee:/Library/Ruby/Gems/1.8/gems/packetfu-1.0.0/examples$ sudo ruby arphood.rb 
Fetching the oui.txt from IEEE, it'll be a second. Avoid this with arphood.rb <filename>.
arphood.rb:30:in `require': no such file to load -- packetfu (LoadError)
    from arphood.rb:30:in `arp_everyone'
    from arphood.rb:51

As you can see packetfu is installed in /Library/Ruby/Gems/1.8/gems/, but ruby cant find it...

Answer 1

that's because you're not in the directory where packetfu.rb file lies and there's no require 'rubygems' to add the gems paths in your script