вопрос по bash

#!/bin/sh

VARIABLE_1=1
VARIABLE_2=2
VARIABLE_3=3

for i in 1 2 3
do
    eval echo \$VARIABLE_$i
done

VARIABLE[1]=$VARIABLE_1
VARIABLE[2]=$VARIABLE_2
VARIABLE[3]=$VARIABLE_3
for i in 1 2 3; do
	indeх=$i
	echo ${VARIABLE[$index]} 
done

а зачем лишняя переменная index?

VARIABLE_1=1
VARIABLE_2=2
VARIABLE_3=3

for i in 1 2 3; do
    var="VARIABLE_$i"
    echo ${!var}
done