#used memory Kbytes
used=`ps -A -o "size" | sed -n '2,$p' | awk '{a+=$1} END {printf("%d\n", a);}'`

#free memory Kbytes
free=`sar -r 1 3 | sed -n '$p' | awk '{print $2}'`
freeK=`expr $free \* 4`

#total K
totalK=`expr $used + $freeK`
echo $totalK":"$used