snaps=($root_dir/btrbk/$subvol_dir.20*) # Assumes we are in the 21st century.
if [[ ! ${snaps[*]} ]]; then
# no snapshots yet
snaps=($root_dir/btrbk/$subvol_dir.20*) # Assumes we are in the 21st century.
if [[ ! ${snaps[*]} ]]; then
# no snapshots yet