config.sample.json

{
  "key": "get it from https://trello.com/app-key",
  "token": "go to https://developers.trello.com/sandbox, open your browser's web developer console, click Execute in sandbox UI, take token from the request url in the network tab",
  "backupDirectory": "/home/user/backup/trello",
  "boards": {
    "89ABCDEF": "board-name"
  }
}