在特定索引处将值分配给数组

您好，我正在尝试编写一个脚本来更新从文件读取的行，到目前为止，一切正常，除了最后提到的以下行

这是我的脚本：

#!/bin/bash     

#INITIALIZE PATHS
DB_PATH=${1}      
DATA_PATH="$DB_PATH/data/"
METADATA_PATH="$DB_PATH/metadata"   

#LOAD THE META DB FILE AND READ DATABASE NAME IN DB_NAME 
#READ ALSO COLUMNS IN AN ARRAY CALLED TABLE_NAMES                      
METADATA_LOAD=$(<"$METADATA_PATH/DB")
IFS=$'+'
read -a NAMES <<< "$METADATA_LOAD"



#PROMPET FOR TABLE TO UPDATE
echo ""
echo ""
echo ""
echo "You Currently Working with Database ${NAMES[0]}" 
echo ""
echo "You Have The Following Tables to Choose From :"
IFS=' '
for token in ${NAMES[@]:1}
do
echo "  $token"
done
echo ""
echo ""
echo ""
echo "Please Write The Name Of The Table You Want To Update :"
read CURRENT_TABLE


#Form META DATA TABLE FILE PATH
TABLE_DATA_PATH="$DB_PATH/data/$CURRENT_TABLE"
TABLE_METADATA_PATH="$DB_PATH/metadata/$CURRENT_TABLE"


#PROMPET WHICH COLUMN IS NEEDED TO CHECK FOR EQUALITY
echo ""
echo ""
echo ""
echo "The Table You Selected Have The Following Columns"
i=0 
TABLE_METADATA=$(<"$TABLE_METADATA_PATH")
IFS='+'
read -a CURRENT_TABLE_META <<< "$TABLE_METADATA"
IFS=' '
for token in ${CURRENT_TABLE_META[@]:1}
do
i=$(($i+1))
echo $i $token
done
echo "Please Enter The Number Column to Check For Equality"
read TEST_COLUMN_NUM
echo ""
echo ""
echo "Please Enter The Column Value to Check For Equality"
read TEST_COLUMN_VAL

echo "Please Enter The Column Number to Modify"
read MODIFY_COLUMN_NUM

echo "Please Enter The New Column Value"
read MODIFY_COLUMN_VAL

#Form DATA TABLE FILE PATH
TABLE_DATA=$(<"$TABLE_DATA_PATH") 


IFS=' '
read -a ROWS_ARRAY <<< "$TABLE_DATA"  




for CURRENT_ROW_INDEX in ${!ROWS_ARRAY[@]}
do

  IFS=':'
  read -a COLUMNS_ARRAY <<< "${ROWS_ARRAY[CURRENT_ROW_INDEX]}"

   for CURRENT_COL_INDEX in ${!COLUMNS_ARRAY[@]} 
   do

       if [[ ${COLUMNS_ARRAY[$CURRENT_COL_INDEX]} == $TEST_COLUMN_VAL  &&  $CURRENT_COL_INDEX -eq $(($TEST_COLUMN_NUM-1)) ]]
       then

           IFS=' '
           COLUMNS_ARRAY[$MODIFY_COLUMN_NUM] = "ABC"



       fi   

   done
done

我还没有完成脚本，但是在该行出现错误：

 COLUMNS_ARRAY[$MODIFY_COLUMN_NUM] = "ABC"

它给我错误

./Update：第91行：COLUMNS_ARRAY [3]：找不到命令

我想在给定索引处分配给数组以替换旧值，请帮助我了解错误的原因以及如何解决