#!/bin/sh

if [ "$1" = "-w" ] && [ "$2" -gt "0" ] && [ "$3" = "-c" ] && [ "$4" -gt "0" ] ; then
	warn=$2
	crit=$4
	SYSCTL_FILE='/home/nagios/sysctl.temp'
	SYSCTL=$(/sbin/sysctl -a > $SYSCTL_FILE)||exit 3
	#echo $SYSCTL
	TOTAL_MEM=`grep 'hw.physmem:' $SYSCTL_FILE | cut -d":" -f2`
	#echo "total mem" $TOTAL_MEM 
	TOTAL_MEM_MB=`expr $TOTAL_MEM / 1024 / 1024`
	#echo "total mem in MB" $TOTAL_MEM_MB
	PAGESIZE=`grep 'hw.pagesize:' $SYSCTL_FILE | cut -d":" -f2`
	#echo "pagesize" $PAGESIZE
        ACTIVE_COUNT=`grep 'vm.stats.vm.v_active_count:' $SYSCTL_FILE | cut -d":" -f2`
        #echo "active_count" $ACTIVE_COUNT
	MEM_ACTIVE=`expr $ACTIVE_COUNT \* $PAGESIZE` 
        #echo "mem active" $MEM_ACTIVE
        INACTIVE_COUNT=`grep 'vm.stats.vm.v_inactive_count:' $SYSCTL_FILE | cut -d":" -f2`
        #echo "inactive_count" $INACTIVE_COUNT
        MEM_INACTIVE=`expr $INACTIVE_COUNT \* $PAGESIZE`
        #echo "mem inactive" $MEM_INACTIVE
        CACHE_COUNT=`grep 'vm.stats.vm.v_cache_count:' $SYSCTL_FILE | cut -d":" -f2`
        #echo "cache_count" $CACHE_COUNT
        MEM_CACHE=`expr $CACHE_COUNT \* $PAGESIZE`
        #echo "mem cache" $MEM_CACHE
        FREE_COUNT=`grep 'vm.stats.vm.v_free_count:' $SYSCTL_FILE | cut -d":" -f2`
        #echo "free_count" $FREE_COUNT
        MEM_FREE=`expr $FREE_COUNT \* $PAGESIZE`
        #echo "mem free" $MEM_FREE

        FREE_MEM=`expr $MEM_INACTIVE + $MEM_CACHE + $MEM_FREE`
        #echo "free mem" $FREE_MEM
        #FREE_MEM_KB=`expr $FREE_MEM / 1024`
        #echo "free mem in KB" $FREE_MEM_KB
	FREE_MEM_MB=`expr $FREE_MEM / 1024 / 1024`
	#echo "free mem in MB" $FREE_MEM_MB
	USED_MEM=`expr $TOTAL_MEM - $FREE_MEM`
	#echo "used mem" $USED_MEM
	USED_MEM_MB=`expr $USED_MEM / 1024`
	#echo "used mem in MB" $USED_MEM
	USED_MEM_PER=`expr $USED_MEM \* 100 / $TOTAL_MEM` 
	#echo "used mem %" $USED_MEM_PER

        if [ $USED_MEM_PER -ge $warn ];then
                if [ $USED_MEM_PER -ge $crit ]; then
                echo "CRITICAL - Memory Usage = $USED_MEM_PER%|MEM=$USED_MEM_PER;;;;"
                exit 2
        	else
                echo "WARNING - Memory Usage = $USED_MEM_PER%|MEM=$USED_MEM_PER;;;;"
                exit 1
        	fi
	else
                echo "OK - Memory Usage = $USED_MEM_PER%|MEM=$USED_MEM_PER;;;;"
        	exit 0
	fi
	
else
        echo "check_mem.sh - Nagios Plugin for checking memory usage"
        echo ""
        echo "Usage:	check_mem.sh -w <warnlevel> -c <critlevel>"
        exit 3
fi