If the designated destination drive is unmounted, Grsync fills up the o/s partition instead of just mounting it, or aborting. How do I prevent that?

I usually remember to check to see that it's mounted, but sometimes I forget, with very bad results.

Thanks for any help.

ra@ra-main:~$ cat /etc/fstab

/etc/fstab: static file system information.

Use 'blkid' to print the universally unique identifier for a

device; this may be used with UUID= as a more robust way to name devices

that works even if disks are added and removed. See fstab(5).

/ was on /dev/sdc3 during installation

UUID=557ba3eb-2dcc-4b03-964b-f12f509c4faa / ext4 errors=remount-ro 0 1

/boot/efi was on /dev/sda3 during installation

#UUID=D305-EBF0 /boot/efi vfat umask=0077 0 1 /swapfile none swap sw 0 0 UUID=0399-667C /boot/efi vfat defaults 0 1 LABEL=Grsync /mnt/Grsync auto nosuid,nodev,nofail,x-gvfs-show,x-gvfs-name=Grsync 0 0 ra@ra-main:~$ ^C