Value not getting assigned to array element Bash script - arrays

Question

I am working on the below script.
I don't understand why I am unable to assign the value to the array and when I print the array elements I only get arr[0], the rest of elements are empty
Is there a more efficient way to match l_num between fields rt_h and rt_f extracted from rt_facts file?
$ bash -version
GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)
$ cat rt_facts
T5 1 2:8 47:9 44
T14 2 48:8 93:9 44
T15 3 94:8 96:9 1
here is the filtered file:
$cat filtered_file
12 4046580009982686 05072021 24692161126100379438583 44442
54 4046580009982686 05072021 24692161126100379438583 44442
95 4046580009982686 05072021 24692161126100379438583 44442
In this script, I am trying to match a string in the filtered file using line number from the original file.
bash-4.1$ vi comb_rt_ct.ksh
#!/bin/bash
rows=1
cols=$(($(cat rt_facts | wc -l) + 1))
declare -a arr #=( $(for i in {1..$cols}; do echo 0; done) )
echo "cols " $cols
for l_num in $(grep '4046580009982686 05072021 24692161126100379438583 44442' filtered_file | cut -d" " -f 1)
do
arr[0]="4046580009982686 05072021 24692161126100379438583 44442"
echo "l_num " $l_num
cat rt_facts | while IFS=" " read -r lineStr
do
line=( $lineStr )
#echo ${line[*]}
rt_h=$(echo ${line[2]} | cut -d":" -f 1)
rt_f=$(echo ${line[3]} | cut -d":" -f 1)
if (( l_num > $rt_h && l_num < $rt_f )); then
echo "rt_h rt_f " $rt_h " " $rt_f
echo "line[*] " ${line[*]}
i=${line[1]}
echo "i " $i
if [[ -z "${arr[$i]}" ]]; then
echo "empty"
arr[$i]=0
fi
(( arr[$i]++ ))
echo "arr[$i] "${arr[$i]}
#echo ${line[0]}
break
fi
done
echo
done
echo ${arr[#]}
echo ${arr[*]}
echo ${arr[2]}
Here is the output when I run the script:
bash-4.1$ sh comb_rt_ct.ksh
cols 4
l_num 12
rt_h rt_f 2 47
line[*] T5 1 2:8 47:9 44
i 1
empty
arr[1] 1
l_num 54
rt_h rt_f 48 93
line[*] T14 2 48:8 93:9 44
i 2
empty
arr[2] 1
l_num 95
rt_h rt_f 94 96
line[*] T15 3 94:8 96:9 1
i 3
empty
arr[3] 1
4046580009982686 05072021 24692161126100379438583 44442
4046580009982686 05072021 24692161126100379438583 44442
bash-4.1$

Answer 1

As #glennjackman has pointed out, the question needs to be updated to provide a minimal, reproducible example; so I'm skipping trying to reverse engineer the intent of the script (or figure out the content of the file named filtered_file) and instead focus on one item of interest:
cat t_facts | while IFS=" " read
...
<assign_values_to_array>
...
done
The | while ... invokes a subshell; new values are assigned to the arr[] array within this subshell.
In ksh, when exiting the subshell, the newly updated arr[] values are (effectively) passed to the calling/parent process.
In bash, when exiting the subshell, the newly updated arr[] values are discarded when returning to the calling/parent process.
Because OP's code is running under bash (#!/bin/bash), the changes to arr[] are lost upon exiting the subshell; this in turn means the calling/parent process 'still' has the same initial value in arr[], namely:
arr[0]="4046580009982686 05072021 24692161126100379438583 44442"
One method to address this issue, which should work in ksh and bash:
while IFS=" " read
...
<assign_value_to_array>
...
done < t_facts
This eliminates the subshell invocation and therefore allows the new array assignments to be made in the main process.
Again, I haven't attempted to understand the overall logic of the script, but fwiw ... I'd suggest OP make the suggested code change to the while loop (to eliminate the subshell invocation) to see if the arr[] array is populated with the desired results.