The cross-platform way to stream an OS image to a device

Install etcher-image-write by running:

$ npm install --save etcher-image-write

NOTICE: You might need to run this function as sudo/administrator to avoid permission issues.

We recommend passing file descriptors opened with rs+ flags.

The returned EventEmitter instance emits the following events:

• progress: A progress event that passes a state object of the form:

{
  type: 'write' // possible values: 'write', 'check'.
  percentage: 9.05,
  transferred: 949624,
  length: 10485760,
  remaining: 9536136,
  eta: 10,
  runtime: 0,
  delta: 295396,
  speed: 949624
}

• error: An error event.
• done: An event emitted with a boolean success value.

Enabling the check option is useful to ensure the image was successfully written to the device. This is checked by calculating and comparing checksums from both the original image and the data written to the device.

The transform option is used to handle cases like decompression of an image on the fly. The stream is piped through this transform stream after the progress stream and before any writing and alignment.

This allows the progress to be accurately displayed even when the client doesn't know the final uncompressed size.

For example, to handle writing a compressed file, you pass the compressed stream to .write(), pass the compressed stream size, and a transform stream to decompress the file.

Kind: static method of imageWrite
Summary: Write a readable stream to a device
Returns: EventEmitter - emitter
Access: public

Example

var emitter = imageWrite.write({
  fd: fs.openSync('/dev/rdisk2', 'rs+'), // '\\\\.\\PHYSICALDRIVE1' in Windows, for example.
  device: '/dev/rdisk2',
  size: 2014314496
}, {
  stream: fs.createReadStream('my/image'),
  size: fs.statSync('my/image').size
}, {
  check: true
});

emitter.on('progress', (state) => {
  console.log(state);
});

emitter.on('error', (error) => {
  console.error(error);
});

emitter.on('done', (results) => {
  console.log('Success!');
});

The errors we emit can be identified by their code and type properties.

Consult this file for a list of defined errors.

If you're having any problem, please raise an issue on GitHub and the Resin.io team will be happy to help.

To run the full test suite (Node & Electron), you'll need to have Electron installed either globally or locally in the repository (npm install [--global] electron).

Run the test suite by doing:

$ npm test

To run only the Node or Electron tests, respectively:

$ npm run test-node # OR
$ npm run test-electron

• Issue Tracker: github.com/resin-io-modules/etcher-image-write/issues
• Source Code: github.com/resin-io-modules/etcher-image-write

Before submitting a PR, please make sure that you include tests, and that jshint runs without any warning:

$ npm run lint

etcher-image-write is free software, and may be redistributed under the terms specified in the license.