Failed to start rsyncd.service: Unit rsyncd.service not found.

If you are encountering the error message "Failed to start rsyncd.service: Unit rsyncd.service not found," it means that the `rsyncd.service` unit file is not present on your system.

To resolve this issue, you can try reinstalling the rsync package on your system. The exact command may vary depending on your Linux distribution.

For example, on Ubuntu or Debian, you can use the following command:

sudo apt-get install --reinstall rsync

On CentOS or RHEL, you can use the following command:

sudo yum reinstall rsync

After reinstalling rsync, you should be able to start the `rsyncd.service` without encountering the "Unit rsyncd.service not found" error.