Non-root access

The control socket is mode 0660 and owned by cellar:cellar. By default only root can talk to it; to run cellar without sudo, add your user to the cellar group (created by systemd-sysusers from contrib/systemd/cellar.sysusers).

Warning: The cellar group grants local control-plane access equivalent to root for CLI operations against the socket.

Add your user to the cellar group.
```
sudo usermod -aG cellar $USER
```
Log out and log back in so that your group membership is re-evaluated. You can also activate the group in the current shell:
```
newgrp cellar
```
Verify that you can run cellar without sudo (with cellard already running):
```
cellar status
```