Bash_4

#!/bin/bash


WEBSITE=$1
shift 1

if [ $1 == "-t" ]
then
   time=$2
   shift 2
else
   time=5
fi
command=$*
old=plik1
new=plik2
wget $WEBSITE -O $new -q
while true
do
   mv $new $old
   sleep $time
   wget $WEBSITE -O $new -q
if [ $new -nt $old ]
then
   $command
else
    echo no change
fi
done