# File lib/bundler/cli/exec.rb, line 19
    def run
      ui = Bundler.ui
      raise ArgumentError if cmd.nil?

      # First, try to exec directly to something in PATH
      SharedHelpers.set_bundle_environment
      bin_path = Bundler.which(@cmd)
      if bin_path
        Bundler.ui = nil
        Kernel.exec(bin_path, *args)
      end

      # If that didn't work, set up the whole bundle
      Bundler.definition.validate_ruby!
      Bundler.load.setup_environment
      Bundler.ui = nil
      Kernel.exec(@cmd, *args)
    rescue Errno::EACCES, Errno::ENOEXEC
      Bundler.ui = ui
      Bundler.ui.error "bundler: not executable: #{cmd}"
      exit 126
    rescue Errno::ENOENT
      Bundler.ui = ui
      Bundler.ui.error "bundler: command not found: #{cmd}"
      Bundler.ui.warn "Install missing gem executables with `bundle install`"
      exit 127
    rescue ArgumentError
      Bundler.ui = ui
      Bundler.ui.error "bundler: exec needs a command to run"
      exit 128
    end