Which command is used to send messages between Samba services within the system?

The command used to send messages between Samba services within the system is smbcontrol. This utility facilitates communication with Samba daemons, allowing the user to send control commands or messages to an already running Samba process, such as smbd or nmbd. By using smbcontrol, administrators can manage Samba services effectively without needing to restart the service for certain tasks or notifications.

For example, if an administrator wants to reload the configuration of a Samba service without downtime, they can use smbcontrol to send a specific command to the process. This capability enhances the overall management of Samba in a mixed environment.

The other options do not represent valid commands for the function specified. Therefore, smbcontrol is the correct choice for sending inter-service messages in a Samba environment.