#!/bin/bash

RAMUSAGE=$(free | awk '/Mem/{printf("RAM Usage: %d\n"), $3/$2*100}'| awk '{print $3}')

if [ "$RAMUSAGE" -ge 80 ];
then
    echo "CRITICAL: RAM Usage at $RAMUSAGE %"
    exit 2;
elif [ "$RAMUSAGE" -ge 65 ];
then
    echo "WARNING: RAM Usage at $RAMUSAGE %"
    exit 1;
else
    echo "OK: RAM Usage at $RAMUSAGE %"
fi