1.有m1.txt m2.txt m3.txt m4.txt，分别创建出对应的目录，m1 m2 m3 m4 并把文件移动到对应的目录下

1.sh

#!/bin/bash

touch m1.txt m2.txt m3.txt m4.txt
for ((i = 1; i < 5; i++)); do
    mkdir m$i
    mv m$i.txt m$i
done

2.使用break关键字打印九九乘法表，提示：printf "%d * %d = %d" $i $j $((i*j))

2.sh

#!/bin/bash

for ((i = 1; i <= 9; i++)); do

    for ((j = 1; j <= 9; j++)); do
        printf "%d * %d = %d \t" $i $j $((i * j))
        if ((i <= j)); then
            break
        fi
    done
    printf "\n"
done