#!/bin/bash

LIMIT=90

TOTAL=$(free -mh | grep Mem | awk '{ gsub("G", ""); print $6 }');

USED=$(free -mh | grep Mem | awk '{ gsub("G", ""); print $3 }');
CACHE=$(free -mh | grep Mem | awk '{ gsub("G", ""); print $6 }');

ALL_USAGE=$(echo "$USED + $CACHE" | bc);
PERCENTAGE=$(echo "$ALL_USAGE / $TOTAL * 100" | bc);

echo $ALL_USAGE

if (test $PERCENTAGE -gt $LIMIT); then
    echo 1 > /proc/sys/vm/drop_caches
fi