shell的随机数

bash默认有一个$RANDOM的变量, 默认范围是0~32767.

使用set|grep RANDOM查看上一次产生的随机数

[root@server shell02]# echo $RANDOM
15832
[root@server shell02]# set |grep RANDOM
RANDOM=15832
[root@server shell02]#

产生0~1之间的随机数

[root@server shell02]# echo $[$RANDOM%2]
0
[root@server shell02]# echo $[$RANDOM%2]
0
[root@server shell02]# echo $[$RANDOM%2]
1

产生0~2的随机数

[root@server shell02]# echo $[$RANDOM%3]
1
[root@server shell02]# echo $[$RANDOM%3]
2
[root@server shell02]# echo $[$RANDOM%3]
1
[root@server shell02]# echo $[$RANDOM%3]
2
[root@server shell02]#

产生1~2之间的随机数

[root@server shell02]# echo $[$RANDOM%2+1]
1
[root@server shell02]# echo $[$RANDOM%2+1]
2
[root@server shell02]# echo $[$RANDOM%2+1]
1
[root@server shell02]# echo $[$RANDOM%2+1]
2

产生50~100之间的随机数

[root@server shell02]# echo $[$RANDOM%51+50]
63
[root@server shell02]# echo $[$RANDOM%51+50]
90
[root@server shell02]# echo $[$RANDOM%51+50]
77
[root@server shell02]# echo $[$RANDOM%51+50]
88

产生三位数的随机数

[root@server shell02]# echo $[$RANDOM%900+100]
713
[root@server shell02]# echo $[$RANDOM%900+100]
686
[root@server shell02]# echo $[$RANDOM%900+100]
474
[root@server shell02]# echo $[$RANDOM%900+100]
202

总结一下

产生一个n~m范围内的随机数

使用$RANDOM取余m-n+1，之后加上n就可以了

 猜数字游戏

#!/bin/bash

echo "猜一个1-100的整数,猜对砸蛋:" 

num=$[$RANDOM%100+1]

while true
do
    read -p "请猜:" gnum
    if [ $gnum -gt $num ];then
        echo "大了"
    elif [ $gnum -lt $num ];then
        echo "小了"
    else    
        echo "对了"
        break
    fi
done

echo "砸蛋"