#!/bin/bash
#             total       used       free     shared    buffers     cached
#Mem:       1926908    1618212     308696          0       9732     179340
#-/+ buffers/cache:    1429140     497768
#Swap:      2031608      79512    1952096

while true
do
	MEM_USED=$(free | awk '/^Mem:/{ print $3 }')
	echo -n "Mem: ${MEM_USED}k";
	if [ "$PREV_MEM_USED" ]
	then
		MEM_DIFF=$((MEM_USED - PREV_MEM_USED))
		[ $MEM_DIFF -gt 0 ] && SIGN='+' || SIGN=''
		echo -n " (${SIGN}${MEM_DIFF}k)"
	fi
	PREV_MEM_USED=$MEM_USED

	SWAP_USED=$(free | awk '/^Swap:/{ print $3 }')
	echo -n "  Swap: ${SWAP_USED}k";
	if [ "$PREV_SWAP_USED" ]
	then
		SWAP_DIFF=$((SWAP_USED - PREV_SWAP_USED))
		[ $SWAP_DIFF -gt 0 ] && SIGN='+' || SIGN=''
		echo -n " (${SIGN}${SWAP_DIFF}k)"
	fi
	PREV_SWAP_USED=$SWAP_USED

	TOTAL_USED=$((MEM_USED + SWAP_USED))
	echo -n "  Total: ${TOTAL_USED}k";
	if [ "$PREV_TOTAL_USED" ]
	then
		TOTAL_DIFF=$((TOTAL_USED - PREV_TOTAL_USED))
		[ $TOTAL_DIFF -gt 0 ] && SIGN='+' || SIGN=''
		echo -n " (${SIGN}${TOTAL_DIFF}k)"
	fi
	PREV_TOTAL_USED=$TOTAL_USED

	if [ "$TOTAL_SINCE_START" ]
	then
		SINCE_START_DIFF=$((TOTAL_SINCE_START - $TOTAL_USED))
		[ $SINCE_START_DIFF -gt 0 ] && SIGN='+' || SIGN=''
		echo -n "  Since start: ${SIGN}${SINCE_START_DIFF}k"
	else
		TOTAL_SINCE_START=$TOTAL_USED
	fi

	echo
	sleep 1
done