while read L # reads on lie from input and ssign it to L
do
    [ -n "$L" ] && { ((i++)); echo $L; continue; }
        # if L is not empty then increment i, output L, next iteration of the loop
    until [ $i -eq 10 ] # doesn't need explanation
    do    ((i++)); echo 
    done
    i=0 # reset i for the next 10 count
done < infile

bash -x scriptname