crontab

# do daily/weekly/monthly maintenance
# min	hour	day	    month	weekday	command
*/15	*	    *	    *	    *	    run-parts /etc/periodic/15min
0	    *	    *	    *	    *	    run-parts /etc/periodic/hourly
0	    2	    *	    *	    *	    run-parts /etc/periodic/daily
0	    3	    *	    *	    6	    run-parts /etc/periodic/weekly
0	    5	    1	    *	    *	    run-parts /etc/periodic/monthly
*/15	*	    *	    *	    *	    run-parts /etc/periodic/15min
17      2       1       *       *       /usr/local/bin/lego --path $LEGO_PATH $LEGO_RENEW_COMMAND_ARGS