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1.1 99乘法表

#!/bin/bash

# 打印九九乘法表
for i in {1..9}; do
    for j in $(seq 1 $i); do
        # 打印格式化的乘法公式并避免换行
        echo -n "$j * $i = $((i * j))  "
    done
    # 每一行结束后换行
    echo
done
打印99乘法表

2.1. 判断输入num还是char

#!/bin/bash
read ch
case $ch in
        [a-zA-Z]) // 正则表达式
        echo " It is a letter "
        ;;
        [0-9])
        echo " It is a number "
        ;;
        *)
        echo " It is unknower "
        ;;
esac

• 多个情况

2.2 判断一个数是不是质数

#!/bin/bash
for p in $(seq 10 99);do
for x in $(seq 2 $(($p - 1)));do
if [ $(($p % $x)) -eq 0 ];then
break
fi
done
if [ $x -eq $(($p - 1)) ];then
echo "$p" >> prime.lst
fi
done