   ## Command line options
 
     * `--verbose` - produce detailed output about release assembly
-
+    * `--output` - (Optional) The path to the .fw file used to write the patch
+      firmware. Defaults to `Nerves.Env.firmware_path/1`
   ## Environment variables
 
     * `NERVES_SYSTEM`    - may be set to a local directory to specify the Nerves

        fwup_conf -> ["-c", Path.join(File.cwd!(), fwup_conf)]
      end

    fw = ["-f", Nerves.Env.firmware_path(config)]
    release_path = Path.join(Mix.Project.build_path(), "rel/#{otp_app}")
    output = [release_path]
    args = args ++ fwup_conf ++ rootfs_overlays ++ fw ++ rootfs_priorities ++ output

      Nerves toolchain (C/C++ crosscompiler) that is used
  """

  @switches [verbose: :boolean, output: :string]

  @impl true
  def run(args) do
