file=/tmp/test

ok=0
cmp /tmp/1 /tmp/2 &> /dev/null  && ok=1
if [[ $ok -eq 1 ]] 
then 
   echo "fail check ok"

   while [ ! -s $file ]; do
     echo "$file is empty"
     wget http://link -O /tmp/test
     sleep 3
   done
   cat /tmp/test 

else 
   echo "fail check fail"
    # do some action
fi