See also upstream:
jhack is an opinionated CLI tool to make charm development and debugging easier. For example, with
jhack show-relation you can pretty-print databags from two related applications and with
jhack tail you can watch what events are being fired on what units in real time.
If you install the snap, you’ll need to
sudo snap connect jhack:dot-local-share-juju snapd to give jhack read/write access to your
~/.local/share/juju juju data folder.
jhack without any argument to see a list of toplevel commands and some subcommands.