By default, Virtualmin will just use the `mv` command to move a domain's home directory when needed, such as when a domain is renamed. However, this may not be appropriate in cases where each virtual server is on it's own filesystem, such as a ZFS mount.

In cases like this, you can set this field to a command or script that will be passed the old and new home directories as parameters. It will also have access to all the environment variables normally passed to pre- and post- modification commands.