Feed Journaler requires the dayone2 command line tool to be installed. This is available from Day One, and can be installed using the following instructions:

  1. Open up Terminal.

  2. Run the following command:

    sudo bash /Applications/Day\ One.app/Contents/Resources/install_cli.sh

  3. When prompted, enter your login password.

More information on this command can be found on Day One help page.