If set, the command or script entered will be run as `root` after the backup is run on schedule. This can be useful for un-mounting removable or remote filesystems to which the backup was be written, or cleaning up old backup files.

The command can discover information about the backup via environment variables starting with `BACKUP_` , like:

`BACKUP_DOMAIN_NAMES`
  Names of all the virtual servers being backed up.

`BACKUP_DEST`
  The destination directory or URL.

`BACKUP_FEATURES`
  Names of all Virtualmin features included in the backup. If `BACKUP_ALL` is set to 1, all features are included.

`BACKUP_STATUS`
  Set to 1 if the backup succeeded, 0 if not.