Shell Script not creating an Array List - arrays

Question

I need help with a strange problem.
This line is not creating an array list, I don't know why.
date_final=($(echo $((date_end-date_start)) | grep -o "[0-9].*")) # PROBLEM
The Whole code is below, the particular array converts a wrong date into a new date but it should be an arraylist, and it creates a single variable instead.
#! /bin/bash
cd /var/lib/zabbixsrv/externalscripts/Manager
rm Unique.txt
declare -a date_final='()'
total_count=$(cat amazon.html 2>/dev/null | jq '.meta.total_count' | grep -o "[^\"]*")
i=0;
for i in $(seq 0 $total_count)
do
#compare=($(cat amazon.html 2>/dev/null | jq ".objects[$i].service_tag" | tr ' ' '\n'))
compare=($(cat amazon.html 2>/dev/null | jq ".objects[$i].conference" | grep -o "[^\"]*" | tr ' ' '\n'))
echo -e ${compare[#]} >> /var/lib/zabbixsrv/externalscripts/Manager/Unique.txt
done
compare1=($(cat Unique.txt | uniq -c | gawk '$1==1{print $2}'))
Number_line=$(echo ${#compare1[#]}) # PROBLEMA RESOLVIDO!!!!
let Number_line-=1
#echo -e ${compare[#]}
for i in $(seq 0 $Number_line)
do
#time=$(cat amazon.html 2>/dev/null | jq '.objects[] | select(.service_tag=='${compare1[$i]}')' | jq ".connect_time" | grep -o "[^\"]*" | grep -o "[^T][0-9].*" | grep -o "[0-9]\{2\}:[0-9]\{2\}:[0-9].")
time=$(cat amazon.html 2>/dev/null | jq '.objects[] | select(.conference=='${compare1[$i]}')' 2>/dev/null | jq ".connect_time" | grep -o "[^\"]*" | grep -o "[^T][0-9].*" | grep -o "[0-9]\{2\}:[0-9]\{2\}:[0-9].")
#echo -e ${compare1[$i]}
date_convert=$(date -d "$time 2 hour ago" +"%H:%M:%S")
date_start=$(date -d "$day $date_convert" +%s)
date_end=$(date +"%s")
date_final=($(echo $((date_end-date_start)) | grep -o "[0-9].*")) # PROBLEM
done
# rm Tenant.txt
#echo ${date_final[0]}
#echo -e ${date_final[#]}
tempo=1
i=0
echo -e $Numero_linha
echo -e ${date_final[#]}
for i in $(seq 0 $Number_line)
do
if ((${date_final[$i]} > $tempo)) 2>/dev/null; then
echo -e ${compare1[$i]}
fi
done
Thanks Very Much

Answer 1

I have used the code from your example to declare date_final and initialize date_start and date_end, and I actually get an array after executing your problematic statement.
I think your problem is you are repeatedly assigning a one-element array to your variable instead of adding elements.
Try this :
date_final+=( $((date_end-date_start)) )
The key here is usine the += operator, which appends instead of assigning. The rest is just cleanup, as you do not need grep to filter for digits (there are only digits in the result of the calculation), and the echo is not required either.