Nagios Plugin to check if a cronjob is enabled/disabled through NRPE, by checking if the line on crontab has been commented out or not.

check_cronjob

#!/bin/bash
#
#    Program : check_cronjob
#

PROGNAME=`basename $0`
REVISION=`echo '$Revision: 0.1 $' | sed -e 's/[^0-9.]//g'`

. /usr/lib/nagios/plugins/utils.sh

print_usage() {
        echo "Usage: $PROGNAME [-C cronjob] [-s status]"
        echo "          -C      Cronjob name"
        echo "          -s      Status to check (enabled/disabled)"
        echo ""
        echo "Usage: $PROGNAME --help"
        echo "Usage: $PROGNAME --version"
}

print_help() {
        print_revision $PROGNAME $REVISION
        echo ""
        echo "Nagios Plugin to check if a cronjob is running through NRPE"
        echo ""
        print_usage
        echo ""
        echo "Cronjob Status Check. - Nico Marengo 2013"
        echo ""
        exit 0
#        support
}

exitstatus=$STATE_WARNING #default
MSG="Missing options. Run -h for help"
while test -n "$1"; do
        case "$1" in
                --help)
                        print_help
                        exit $STATE_OK
                        ;;
                -h)
                        print_help
                        exit $STATE_OK
                        ;;
                --version)
                        print_revision $PROGNAME $REVISION
                        exit $STATE_OK
                        ;;
                -V)
                        print_revision $PROGNAME $REVISION
                        exit $STATE_OK
                        ;;
                -C)
                    CRONJOB=$2;
                    shift;
                    ;;
                -s) STATUS=$2;
                    shift;
                ;;

                *)
                        echo "Unknown argument: $1"
                        print_usage
                        exit $STATE_UNKNOWN
                        ;;
        esac
        shift
done

if [ -z "$CRONJOB" ]; then
        exitstatus=$STATE_CRITICAL
        MSG="What Cronjob?"
fi

JOB=`crontab -l | grep "${CRONJOB}" | head -c 1`
DISABLEDSTATUS='#'

if [ -z "$JOB" ]; then
        exitstatus=$STATE_CRITICAL
        MSG="Cronjob not found"
else
        if [ -z "$STATUS" ]; then
                exitstatus=$STATE_CRITICAL
                MSG="What Status?"
        elif [ "$STATUS" = "enabled" ]; then
                if [ "$JOB" != $DISABLEDSTATUS ];then
                        exitstatus=$STATE_OK
                        MSG="OK: enabled"
                elif [ "$JOB" = $DISABLEDSTATUS ];then
                        exitstatus=$STATE_CRITICAL
                        MSG="CRITICAL: disabled"
                fi
        elif [ "$STATUS" = "disabled" ]; then
                if [ "$JOB" != $DISABLEDSTATUS ];then
                        exitstatus=$STATE_CRITICAL
                        MSG="CRITICAL: enabled"
                elif [ "$JOB" = $DISABLEDSTATUS ];then
                        exitstatus=$STATE_OK
                        MSG="OK: disabled"
                fi
        fi
fi

echo $MSG
exit $exitstatus

name_of_your_file.cfg

define service{
        use                             generic-service         ; Name of service template to use
        host_name                       SERVER-HOST-NAME
        service_description             My Cron Check
        check_command                   check_nrpe!check_NAME_cron
        }

nrpe.cfg

command[check_NAME_cron]=/usr/lib/nagios/plugins/check_cronjob -C NAME -s enabled

@re-schneider . Please feel free to re-use, extend, etc. Happy for it to go on MIT license. Thanks for getting in touch.