``` Usage: cat data.json | ./node_modules/.bin/extend-properties [-ah] index.json > data-edited.json Description: Take a list of JSON objects with an `_id` property on standard input and apply changes to it. The changes are based on an index file that is a list of JSON objects with an `id` property and the other properties you want to change. This command is basically a wrapper around the Underscore.js `extend` function and calls it like this: newDoc = _.extend(origDoc, change); Options: -h This help information. -a Update all occurrences of an object, rather than just updating the first or top level occurrence. Be careful when using this on embedded documents, because this can cause conflicts if the embedded document is modified but the referenced doc is not updated. To modify embedded documents properly you should update the source document first and then replace the embedded document so the `_rev` property matches. ```