要在shell中生成随机数，在bash中可以调用$RANDOM，引用一段对RANDOM的介绍。
Each time this is referenced, a random integer between 0 and 32767 is generated. The sequence of random numbers may be initialized by assigning a value to RANDOM. If RANDOM is unset, it loses its special properties, even if it is subsequently reset.

要生成一个范围中的随机数,可以用:
declare -i randomnum=$RANDOM*$scale/32767
同样,要使用declare，必须是在bash环境中。

补充:
shell第一行必须是#!/usr/bin/bash或#!/bin/bash，与所使用的shell类型与路径有关。