Icinga Plugin to monitor if cron is alive

cron_alive.sh

#!/bin/bash

# Determine if cron is running
# Comes from https://gist.github.com/3061023

UNKNOWN_STATE=3
CRITICAL_STATE=2
WARNING_STATE=1
OK_STATE=0

CAT=/bin/cat
GREP=/bin/grep
TAIL=/usr/bin/tail
PS=/bin/ps

$PS aux | $GREP 'cron$' | $GREP -v grep
if [ $? == 0 ]; then
        echo "[$(date)] cron is alive!"
        exit ${OK_STATE}
else
        echo "[$(date)] Cron is not there :'("
        echo "[$(date)] /proc/loadavg: $(cat /proc/loadavg)"
        echo "[$(date)] looking for OOM killer victims... (only 15 results, if any)"
        $GREP -i 'killed process' /var/log/*.log | $TAIL -n 15
        echo "[$(date)] finished listing of OOM killer victims"
        exit ${CRITICAL_STATE}
fi