Path to rmt on remote system
For the tar command to write a backup to a remote server, it
must invoke the rmt command on the destination system. This can
normally be left set to Default, but it the source and destination
servers run different operating systems you may need to set this to the
correct path to rmt on the destination. Common paths include
/etc/rmt, /usr/libexec/rmt and /usr/sbin/rmt.