test_file_on_path.rb

def executable_on_path(binary)
  @matches = []

  ENV['PATH'].split(":").each do |path|
    bintest = File.executable?("#{path}/#{binary}")
    curtest = "#{path}/#{binary}"
    @matches << curtest if bintest == true
  end
  case @matches.length
    when 0 then
      false
    when 1 then
      @matches[0]
    else
      false
  end

end