Iterate array in bash v.3 - arrays

Question

I have file.properties, where are keys and values defined:
key1=value1 value2 value3
key2=value4 value5 value6
key3=value7 value8 value9
I want to load lines from the file to array. I cannot use declare -A to create associative array because of bash 3.
In bash 4 my code is:
conf="./file.properties"
init() {
local configiration=$1
if [ -f "$conf" ]
then
while IFS='=' read -r key value
do
configuration[ ${key} ]=$value
done < "$conf"
fi}
declare -A configuration
init configuration
KEY="key value from file"
#KEY="key1" or KEY="key2" or KEY="key3"
SERVERS=${configuration[ $KEY ]}
I want to do the same job in bash 3.
conf="./file.properties"
init () {
key=()
value=()
if [ -f "$conf" ]
then
while IFS='=' read -r key value
do
key+=("$key")
value+=("$value")
done < "$conf"
fi}
init
KEY="key value from file"
#KEY="key1" or KEY="key2" or KEY="key3"
for ((i = 0; i < ${#key[#]}; i++))
do
if [ "${key[$i]}" == "$KEY" ];
then
echo "values: ${value[i]}"
fi
done
In both cases I get the same output, e.g.:
value1 value2 value3
Is my code for bash 3 correct or something has to be revised?

Answer 1

This looks correct to me, as you use an appropriate way to iterate through your arrays considering you just created them prior and know that the arrays' keys will be in 0,1,...,n-1 for your arrays of size n. The array+=(elements) operator always places elements into array starting at array's last index + 1.
The only case where I would iterate through an array differently is if it were not guaranteed that the indices are in [0,n). For example:
declare -ai roots=();
declare -i x y;
for ((x=0; x<4; roots[x*x]=x,++x)) do :; done;
for y in "${!roots[#]}"; do
printf 'sqrt(%d) = %d\n' $y ${roots[y]};
done;
By expanding the indices of roots using "${!roots[#]}"to iterate across it, we get the following output:
sqrt(0) = 0
sqrt(1) = 1
sqrt(4) = 2
sqrt(9) = 3
In cases like this, we have to avoid the arithmetic for loop to avoid something like the following from occurring:
$ for((i=0;i<${#roots[#]};++i)); do echo "${roots[i]}"; done;
0
1
 
 
The only change I would make is to use [[ instead of [ to perform string comparison, as it is a bash builtin which is safer and more efficient to use in general. Also, I believe you need either a newline or a ; before your } to close your init function.