etcher/docs/CLI.md
Juan Cruz Viotti a93c28ab20 docs(CLI.md): write the CLI.md document (#511)
This document explains what the Etcher CLI is, how can be used, and some
peculiarities, like `--robot` and exit codes.

Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>
2016-06-22 17:06:06 -04:00

2.2 KiB

Etcher CLI

The Etcher CLI is a command-line tool that aims to provide all the benefits of the Etcher desktop application in a way that can be ran from a terminal, or even used from a script.

In fact, the Etcher desktop application is simply a wrapper around the CLI, which the place where the actual writing logic takes place.

Running

We are not oficially releasing the Etcher CLI as a separate package yet, but you can run it locally with the following steps:

  • Clone the Etcher repository.
git clone https://github.com/resin-io/etcher
  • Install the dependencies, using the instructions from CONTRIBUTING.md.

  • Run the Etcher CLI from bin/etcher.

./bin/etcher --help

Options

  --help, -h     show help
  --version, -v  show version number
  --drive, -d    drive
  --check, -c    validate write
  --robot, -r    parse-able output without interactivity
  --log, -l      output log file
  --yes, -y      confirm non-interactively
  --unmount, -u  unmount on success

The robot option

The --robot option is very particular since it allows other applications to easily consume the output of the Etcher CLI in real-time. When using the --robot option, the --yes option is implicit, therefore you need to manually specify --drive.

When --robot is used, the program will output JSON lines containing the progress state and other useful information. For example:

$ sudo etcher image.iso --robot --drive /dev/disk2
{"command":"progress","data":{"type":"write","percentage":1,"eta":130,"speed":1703936}}
...
{"command":"progress","data":{"type":"check","percentage":100,"eta":0,"speed":17180514}}
{"command":"done","data":{"passedValidation":true,"sourceChecksum":"27c39a5d"}}

The command property can be used to determine the action taking place, while the data property contains extra information related to the command.

Exit codes

The Etcher CLI uses certain exit codes to signal the result of the operation. These are documented in lib/src/exit-codes.js and are also printed on the Etcher CLI help page.