memory linux

#!/bin/bash
# IMPORTANT:
# by default outputs physical memory
# - Linux only
# - User which is running the script should have
# same primary group as the one running oracle,
# otherwise ipcs will report 0 instead of
# actual shared memory. Being in the same
# groups may be not be enough

MEM_TOTAL=$( free -k|awk '/Mem/ {m=$2 * 1024; printf("%d", m)}' )
MEM_USED1=$( free -k|awk '/Mem/ {m=$3 * 1024; printf("%d", m)}' )
BUFF_USED=$( free -k|awk '/Mem/ {m=$6 * 1024; printf("%d", m)}' )

SHARED_USED=$( ipcs -m|awk '/0x/ {sum +=$5}; END {print sum}' )
SHARED_USED2=$( df -P -B1 /dev/shm|tail -n1 |awk '{print $3}' )
FREE=$( free -b|awk '/Mem/ {print $4}' )
CACHED=$( free -b | awk '/Mem/ {print $7}' )

#let MEM_USED=$MEM_USED1+$SHARED_USED+$SHARED_USED2+$BUFF_USED
let MEM_FREE=$FREE+$CACHED-$SHARED_USED-$SHARED_USED2
let MEM_USED=$MEM_TOTAL-$MEM_FREE
let MEM_USED_PRC=$MEM_USED*100/$MEM_TOTAL
let MEM_FREE_MB=$MEM_FREE/1024/1024
#let MEM_FREE_MB=($MEM_TOTAL-$MEM_USED)/1024/1024
#echo "PRC=$MEM_USED_PRC FREE=$MEM_FREE_MB"

SWAP_TOTAL=$( free -b|awk '/Swap/ {print $2}' )
SWAP_USED=$( free -b|awk '/Swap/ {print $3}' )
let SWAP_USED_PRC=$SWAP_USED*100/$SWAP_TOTAL
let SWAP_FREE_MB=($SWAP_TOTAL-$SWAP_USED)/1024/1024

let VIRT_TOTAL=$MEM_TOTAL+$SWAP_TOTAL
let VIRT_USED=$MEM_USED+$SWAP_USED
let VIRT_USED_PRC=$VIRT_USED*100/$VIRT_TOTAL
let VIRT_FREE=($VIRT_TOTAL-$VIRT_USED)/1024/1024

case "$1" in
        virt*)  echo "$VIRT_USED_PRC $VIRT_FREE";;
        swap)   echo "$SWAP_USED_PRC $SWAP_FREE_MB";;
        *)      echo "$MEM_USED_PRC $MEM_FREE_MB";;
esac