#!/bin/bash

if [ $# -ne 2 ]; then
	cat << EOF
Check memory usage. Values: used%
USAGE: $0 <WARN> <CRIT>
Note: USED=TOTAL-AVAILABLE
EOF
	exit 3
fi

WARN=$1
CRIT=$2

if ! which free > /dev/null; then
	echo UNKNOWN: free command not found.
	exit 3
fi

TOTAL=0
USED=0
AVAIL=0

while read line; do
	ARR=( $line )
	[ ${ARR[0]} != "Mem:" ] && continue

	TOTAL=${ARR[1]}
	AVAIL=${ARR[6]}
	USED=$(($TOTAL-$AVAIL))

	break
done <<< $(free | tail -n -2)

PERCENT_USED=$(echo "scale=4; $USED / $TOTAL * 100 " | bc -l)
PERCENT_USED=${PERCENT_USED%00}
PERCENT_USED_INT=0${PERCENT_USED%.*}

if [ $PERCENT_USED_INT -ge $CRIT ]; then
	RET=2
	echo -n "Memory CRITICAL: "
elif [ $PERCENT_USED_INT -ge $WARN ]; then
	RET=1
	echo -n "Memory WARNING: "
else
	RET=0
	echo -n "Memory OK: "
fi

echo "$PERCENT_USED% Used | percent_used=$PERCENT_USED% total=$TOTAL available=$AVAIL"
exit $RET