SublimeText2 - Check ruby syntax after save file

Ruby.sublime-build

# Edit file: /path/to/SublimeText2/Packages/Ruby/Ruby.sublime-build
{
    "cmd": ["/home/edgar/.rvm/rubies/ruby-1.9.2-p290/bin/ruby", "-cw", "$file"],
    "file_regex": "^(...*?):([0-9]*):?([0-9]*)",
    "selector": "source.ruby"
}

ruby_check.py

# Copy this to: /path/to/SublimeText2/Packages/User/ruby_check.py
import sublime, sublime_plugin

class rubyCheck(sublime_plugin.EventListener):
    def on_post_save(self, view):
        if view.file_name()[-3:] == '.rb':
            view.window().run_command("build")

It returns a "No Build System" message after every save process. I'm using ruby 1.9.2p180.

I tested on mac and works nice. You should edit the existent Ruby.sublime-build and change the ruby for the rvm path, in my case is:
/Users/edgar/.rvm/rubies/ruby-1.9.2-p290/bin/ruby

these files in mac are in Library/Application Support/Sublime Text 2/Packages

It was a missing comma after the "-cw" flag. It works beatiful now.

Thank's!