BASH 腳本未在函數中加入變數

Question

我的帶有加法函數的腳本不會對我根據讀取分配數值的兩個變數執行加運算子 (+)。使用其他運算符，其他功能將正常運作。

腳本：

#!/bin/bash                                              

function addition {                                      
   FNUM1=$1                                              
   FNUM2=$2                                              
   RESULT=$((FNUM1+FNUM2))                               
   echo "RESULT: $RESULT"                                          
}                                                        

function subtraction {                                    
   FNUM1=$1                                              
   FNUM2=$2                                              
   RESULT=$((FNUM1-FNUM2))                               
   echo "RESULT: $RESULT"                                          
}                                                        

function multiplication {                                       
   FNUM1=$1                                              
   FNUM2=$2                                              
   RESULT=$((FNUM1*FNUM2))                               
   echo "RESULT: $RESULT"                                          
}                                                        

function division {                                      
   FNUM1=$1                                              
   FNUM2=$2                                              
   RESULT=$((FNUM1/FNUM2))                               
   echo "RESULT: $RESULT"                                          
}                                                        

clear
echo "Please select a calculation to make!"              
echo "Choose how to you want to calculate two numbers"

COUNTER=0                                                

while [ $COUNTER -eq 0 ]                                 
do                                                       
   echo ""                                               
   echo "1 - addition"                                   
   echo "2 - subtraction"                                
   echo "3 - multiplication"                             
   echo "4 - division"                                   
   echo "5 - QUIT"                                       

   read CHOICE                                           

   case $CHOICE in                                       
      1)                                                 
         echo "YOU CHOSE ADDITION!"                      
         echo "Enter first number: "                     
         read NUM1                                       
         echo "Added by: "                               
         read NUM2                                       
         addition $NUM1 $NUM                             
         ;;                                              
      2)
         echo "YOU CHOSE SUBTRACTION!"                   
         echo "Enter first number: "                     
         read NUM1                                       
         echo "Subtracted by: "                          
         read NUM2                                       
         subtraction $NUM1 $NUM2                         
         ;;                                              
      3)                                                 
         echo "YOU CHOSE MULTIPLICATION!"                
         echo "Enter first number: "                     
         read NUM1                                       
         echo "Multiplied by: "                          
         read NUM2                                       
         multiplication $NUM1 $NUM2                      
         ;;                                              
      4)                                                 
         echo "YOU CHOSE DIVISION!"                      
         echo "Enter first number: "                     
         read NUM1                                       
         echo "Divided by: "                             
         read NUM2                                       
         division $NUM1 $NUM2                            
         ;;                                              
      5)                                                 
         COUNTER=$(( $COUNTER + 1 ))                     
         ;;                                              
      *)                                                 
         echo "You must enter a number from 1 through 5!"
   esac                                                  
done                                                                                                      

輸出：

Please select a calculation to make!

Choose how to you want to calculate two numbers
1 - addition
2 - subtraction
3 - multiplication
4 - division
5 - QUIT
1
YOU CHOSE ADDITION!
Enter first number:
24
Added by:
5
RESULT: 24

我希望加法函數將讀取到 FNUM1 和 FNUM2 變數中的值相加。

Answer 1

正如 ilkkachu 評論的那樣，您的添加程式碼中有一個簡單的拼字錯誤：

     echo "Added by: "                               
     read NUM2                                       
     addition $NUM1 $NUM                             

應該：

     echo "Added by: "                               
     read NUM2                                       
     addition $NUM1 $NUM2                

同上 ShellCheck 的評論建議和set -u對於此類錯誤。set -u執行腳本時會給你一個錯誤。

執行參數擴展時，將除特殊參數“@”或“*”之外的未設定變數和參數視為錯誤。錯誤訊息將寫入標準錯誤，並且非互動式 shell 將退出。