firefox custom search

Today I wanted to add a custom search to my Firefox.  It is the search box on the top right corner of Firefox.  By default, I saw:

• Google
• Yahoo
• Amazon
• ...

But what I wanted is urbandictionary.com.  It's so easy to add a custom search in Firefox.  I opened Terminal, login as root, then:

vi /Applications/Firefox.app/Contents/MacOS/searchplugins/urbandictionary.src

I then entered xml code below:

<search
  name="urbandictionary"
  method="GET"
  action="http://www.urbandictionary.com/define.php"
  queryCharset="utf-8">
  <input name="term" user />
</search>

I tested it with MacOSX.  An example here is urbandictionary.com.