Exec into crond in init script

Co-authored-by: Matyas Selmeci <mselmeci@wisc.edu>

Author: mwestphall

opensciencegrid/logrotate/startup.sh

@@ -5,4 +5,6 @@
 echo "$CRON_EXPR /usr/sbin/logrotate $LOGROTATE_OPTIONS $LOGROTATE_CONF" '> /proc/$(cat /var/run/crond.pid)/fd/1 2>&1' | crontab - 
 
 # Start cron in non-daemon (foreground) mode
-crond -n
+exec crond -n
+echo >&2 "Exec failed!"
+exit 255