# `mix firmware.patch`
[🔗](https://github.com/nerves-project/nerves/blob/v1.14.1/lib/mix/tasks/firmware.patch.ex#L7)

Generate a firmware patch from a source and target firmware and output a new
firmware file with the patch contents. The source firmware file

This requires fwup >= 1.6.0

## Command line options

  * `--source` - (Optional) The path to the .fw file used as the source.
    Defaults to the last firmware built.
  * `--target` - (Optional) The path to the .fw file used as the target.
    Defaults to generating a new firmware without overwriting the source.
  * `--output` - (Optional) The path to the .fw file used to write the patch
    firmware. Defaults to `Nerves.Env.firmware_path/1`

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*Consult [api-reference.md](api-reference.md) for complete listing*