Bash 为什么不'；我不能得到正确的乘法输出吗？

我没有得到正确的结果输出。它不是将投入乘以额外成本，而是按原样显示投入。我需要将人数与基于选择可能产生的额外成本相乘

#!/bin/bash

read -p "Number of Adult Tickets:(0 for none) " integer1    
read -p "Number of Junior Tickets:(0 for none) " integer2

echo ""    
echo "$integer1 Adults"    
echo "$integer2 Juniors"
echo ""

num1=$50    
num2=$20    
num3=$5    

echo "Season Pass Add-On:"    
echo "1)Add Seasonal Parking"    
echo "2)Add Season Pass For Theme Park"    
echo "7)Just Buy Tickets For Today"    
echo "8)I wanna exit."

echo ""
read -p "What would the guest like to do? " guest
echo ""    

case $guest in
    1)     
       echo "Add Seasonal Parking"     
       echo ""     
       echo "Add an additional $num1 for every adult pass"     
       echo ""      
       echo "For Adult Tickets "$(( integer1 + num1 ))""      
       echo "For Junior Tickets "$(( integer2 + num1 ))""     
       ;;    
    2)     
       echo "Add Season Pass For Theme Park"     
       echo ""     
       echo "Add an additional $num2 for every adult pass"     
       echo "Add an additional $num3 for every junior pass"     
       echo ""      
       echo "For Junior Tickets "$(( integer2 * num2 ))""      
       echo "For Adult Tickets "$(( integer1 * num3 ))""      
       echo "For Junior Tickets "$(( integer2 * num2 ))""      
       echo "For Adult Tickets "$(( integer1 * num3))""    
       ;; 
    3)     
       echo "Just buy tickets for today"     
       exit 0     
       ;;    
    4)     
       echo "invalid entry. You are exiting"     
       exit 1    
       ;; 
esac     

exit 0

---

问题是美元开始升值

num1=$50
num2=20美元
num3=5美元

美元符号在Bash中有特殊含义，因此它不能作为常规数字使用。在不使用货币的情况下存储这些常量，然后将其添加到结果中

美元符号需要用反斜杠转义，以回音显示

echo "For Adult Tickets \$$(( integer1 + num1 ))"