产生5个随机数的脚本：
#!/bin/bash
MAX=5
i=1
echo "$MAX random numbers are generated:"
while [ "$i" -le $MAX ]
do
number=$RANDOM
echo $number
let "i=i+1"
done
应用之一：在各种登录软件时提示的输入验证码
#! /bin/bash
length=6
i=1
seq=(0 1 2 3 4 6 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z)
num_seq=${#seq[@]}
while [ "$i" -le "$length" ]
do
seqrand[$i]=${seq[$((RANDOM%num_seq))]}
let "i=i+1"
done
#下面是输出结果
echo "The random string is:"
for j in ${seqrand[@]}
do
echo -n $j
done
echo