#!/bin/sh

interval=120
while getopts i: opt;do
 case $opt in
  i)    interval=$OPTARG;;
 esac
done
shift `expr $OPTIND - 1`


if [ "$1" ];then
 fs=$1
else
 fs=.
fi

intervalmins=`echo 4k $interval 60/p|dc`

left=`df $fs|sed 1d|awk '{ print $4 }'`
while true;do
 sleep $interval
 old=$left
 left=`df $fs|sed 1d|awk '{ print $4 }'`
 rate=`echo 4k $old $left - $intervalmins /p|dc`
 min=`echo 4k $left $rate /p|dc`
 hours=`expr \`echo $min|cut -d. -f1\` / 60`
 remmin=`echo $min $hours 60*-p|dc`
 printf "%10i    %3i hours %5.2f min\n" $left $hours $remmin
done