change switch ip when it changes

kk_change_ip.sh

#!/bin/sh

PATH=/usr/bin:/sbin:/bin
SW_FILE=/www/switches.json
NOW_IP=$(ifconfig wlan0 | grep -Eo '[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+' | head -n 1)
OLD_IP=$(jq -r '.switches[0].ip' ${SW_FILE})

if [ ${NOW_IP} != ${OLD_IP} ]; then
    echo "ip changes detected, I'll update the ${SW_FILE}"
    jq --arg v ${NOW_IP} '.switches[0].ip=$v' ${SW_FILE} > /tmp/tmp.json
    mv /tmp/tmp.json ${SW_FILE}
    echo "change ip from ${OLD_IP} to ${NOW_IP}"
else
    echo "nothing to be done"
fi

check ip every 5 minutes by using the cron function.

crontab -e
*/5 * * * * /root/change_ip.sh