+check-subvol-stale ${mountpoints[@]} || die "found stale mountpoints in ${mountpoints[*]}"
+
+# for an initial run, btrbk requires the dir to exist.
+mkdir -p /mnt/root/btrbk
+local_zone=$(date +%z)
+
+if [[ $source ]]; then
+ if ! zone=$(ssh root@$source date +%z); then
+ die failed to ssh to root@$source
+ fi
+ if [[ $zone != $local_zone ]]; then
+ die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
+ fi
+
+else
+
+ sshable=()
+ sshfail=()
+ min_idle_ms=$((1000 * 60 * 15))
+ for h in ${targets[@]}; do
+ if zone=$(ssh root@$h "mkdir -p /mnt/root/btrbk && date +%z"); then
+ if $cron && DISPLAY=:0 xprintidle; then
+ # This is a separate ssh because xprintidle can fail and thats ok.
+ # Ignore this host. i sometimes use a non-main machine for testing or web browsing, knowing that
+ # everything will be wiped by the next backup, but I dont want it to happen as Im using
+ # it from cronjob.
+ continue
+ fi
+ sshable+=($h)
+ if [[ $zone != $local_zone ]]; then
+ die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
+ fi
+ else
+ sshfail+=($h)
+ fi
+ done
+ if [[ ! $sshable ]] || { ! $cron && [[ $sshfail ]]; }; then
+ die "failed to ssh to hosts: ${sshfail[*]}"
+ else
+ if [[ $sshfail ]]; then
+ ret=1
+ echo "$pre error: failed to ssh to ${sshfail[*]} but continuing with other hosts"
+ fi
+ targets=(${sshable[@]})
+ fi
+fi