add wait-until

wait-until

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+# https://stackoverflow.com/questions/645992/sleep-until-a-specific-time-date
+
+until_time=$1
+
+current_epoch=$(date +%s)
+target_epoch=$(date -d $until_time +%s)
+
+sleep_seconds=$(( $target_epoch - $current_epoch ))
+
+echo $sleep_seconds
+# sleep $sleep_seconds