ddwrt-set-datetime-315648.sh

#!/bin/sh
# https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=315648
# update date/time on WAN up and periodically via scheduler

# install into /jffs directory (assumes JFFS has already been initialized)
WANUP_DIR="/jffs/etc/config"
WANUP_SCRIPT="$WANUP_DIR/set-datetime.wanup"

mkdir -p $WANUP_DIR

cat << "EOF" > $WANUP_SCRIPT
#!/bin/sh
(
set -x # comment/uncomment to disable/enable debug mode

NTP_SERVER="time.apple.com"
UPDATE_EVERY=4 # hours
WAN_GW="$(nvram get wan_gateway)"

# don't proceed unless and until WAN is *really* up and ready!
if [[ ! "$WAN_GW" || "$WAN_GW" == "0.0.0.0" ]]; then
    echo "ERROR: wan/isp gateway not found"
    exit 1
fi

# set initial date/time (don't quit until successful)
while ! ntpclient $NTP_SERVER; do sleep 10; done

# older and newer builds use a different version of cron
[ "$(which cron)" ] && CRON="cron" || CRON="crond"

# add job to scheduler to update date/time periodically
stopservice $CRON
echo "* */$UPDATE_EVERY * * * root ntpclient $NTP_SERVER" >> /tmp/crontab
startservice $CRON

exit 0
) 2>&1 | logger -t $(basename $0)[$$]
EOF
chmod +x $WANUP_SCRIPT