Add script to crontab using cru command
#!/bin/sh
# Purpose: script to add the ip check script to cron
# Author: Allan Marcus under GPL version 2.x or above
# /jffs/scripts/services-start
# -------------------------------------------------------------
# cru command
# https://www.cyberciti.biz/faq/how-to-add-cron-job-on-asuswrt-merlin-wifi-router/