In 'bin/rdebug' there is this line:
  output = `ruby -c "#{Debugger::PROG_SCRIPT}" 2>&1`

This is problematic because I don't have 'ruby' in the PATH anyplace.

Here's the error message I get:
  sh: line 1: ruby: command not found

On another platform, it runs the *wrong* ruby version because the other version is in the path earlier.

I don't know how to do this, so I posted a question on stackoverflow:
http://stackoverflow.com/questions/2814077/how-do-i-find-the-ruby-interpreter

Ciao!