shell打印99乘法表

#!/bin/bash
val=10
for (( i = 1 ;i < ${val} ; i++)); do
    for (( y = 1; y <= ${i}; y ++ )); do
        sum=$[${i} * ${y}]
        echo -n "${i} x ${y} = ${sum}    "
    done
    echo ""
done