key change-passphrase

Here's the command-line help for this action in the most recent version of borgmatic. If you're using an older version, some of these flags may not work, and you should instead run the action with --help to see the flags specific to your borgmatic version.

usage: borgmatic key change-passphrase [--repository REPOSITORY] [-h]

Change the passphrase protecting the repository key

key change-passphrase arguments:
  --repository REPOSITORY
                        Path of repository to change the passphrase for,
                        defaults to the configured repository if there is only
                        one, quoted globs supported
  -h, --help            Show this help message and exit