使用SHELL完成两个数字的大小比较-创新互联

简要说明：

提示用户输入两个数字；

判断输入的内容是否都为数字；

数字做计算并反馈结果；

计算完毕后询问客户是否继续使用；

给用户提供随时退出的方法。

[root@lb02 scripts]# cat jisuan2.sh

#!/bin/bash

###thank_oldboy

###2016/3/6

###i wish you all the best.

. /etc/init.d/functions

### read number.

function read_number(){

 read -p "please enter the number1:" num1

 read -p "please enter the number2:" num2

 panduan_number

}

### judge $number1 $number2 both are number.

function panduan_number() {

 expr $num1 + $num2 &>/dev/null

 [ $? -ne 0 ] && {

 [[ $num1 == exit || $num2 == exit ]] && {

  echo "you had choice leave,bye."

  exit 0

 } || {

 echo "USAGE:you must enter two numbers, or enter exit to leave."

 read_number

 }

 } || judge_number

}

### judge continue or exit.

function continue_or_exit() {

 read -p "please enter go to continue or enter out to leave: " str

 case "$str" in

 go)

   read_number

   ;;

 out)

   echo "hope to see you again,bye."

   exit 0

   ;;

 *)

   echo "USAGE:enter go or out:"

   continue_or_exit

   ;;

 esac

}

### expr $number1 $number2.

function judge_number() {

[ $num1 -eq $num2 ] && {

 echo "$num1 equal $num2."

 continue_or_exit

}

[ $num1 -gt $num2 ] && {

 echo "$num1 greater than $num2."

 continue_or_exit

}

[ $num1 -lt $num2 ] && {

 echo "$num1 lower than $num2."

 continue_or_exit

}

}

### the gate of the script.

function main() {

 read_number

}

main

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