#!/bin/sh -

if [ x"$#" = x"2" -a x"$1" = x"-c" ]; then
	continueous=1
	shift
fi

if [ x"$#" != x"1" ]; then
	echo "Usage: $0 <file>"
	exit 2
fi

if ! [ -f "$1" ]; then
	echo "$1" does not exist!
	exit 1
fi

if [ $continueous = 1 ]; then
	lastls=$(ls -l "$1")
	while sleep 1; do
		nextls=$(ls -l "$1")
		( echo "$lastls"; echo "$nextls") |
		grep -v '^total' |
		awk '{ ar[NR] = $5 }
			END { bytes = ar[2] - ar[1];
			bytespersec = bytes;
			print bytespersec / 1024 / 1024 }'

		lastls="$nextls"
	done
else
	( ls -l "$1"; sleep 5; ls -l "$1") |
		grep -v '^total' |
		awk '{ ar[NR] = $5 }
			END { bytes = ar[2] - ar[1];
			bytespersec = bytes / 5;
			print bytespersec / 1024 / 1024 }'
fi