Progress Bar While Looping Script - bash

Question

I would like to show a progress bar while running the following code. I'm calling a script within this code that could take a while depending on the variables passed in. I've tried some of the implementations from How to add a progress bar to a shell script? but have not been able to get them to work. In theory it should continue based off of whether or not the process is still running. If it's still running then show a progress bar.
cat $BLKUPLD | tr -d '\r' | while read line;
do
device_name=`echo $line | cut -d "," -f 1`
quantity_num=`echo $line | cut -d "," -f 2`
bash $SCRIPT $device_name $quantity_num
done
Please let me know if you need additional information.

Answer 1

Below is a progress bar script that will run until the bar is filled.
You will want to change the condition of the outermost while loop to instead check whether your $BLKUPLD has completed, and move the rest of your code inside the while loop where indicated (essentially, you may need to change MAX_ITERATIONS to a boolean condition, and play with where to insert the components of your code within this scaffold).
Ideally you would know how much remaining data you had, and could dynamically set MAX_ITERATIONS accordingly as you enter the loop logic; however, you mentioned that you were okay with having an infinitely looping progress bar as well, which might be the way you have to go if you aren't able to pre-define the end point of your script.
The main premise behind this script that differs from the other thread I linked, is that there are no hardcoded progress points: e.g. "[###__________]33%". Instead, the nested while loops serve to dynamically set the number of hashtags, and also dynamically pad the spacing following the hashtags to maintain a consistent span of progress.
#!/bin/sh
MAX_ITERATIONS=10
WHILE_ITERATOR=0
while [ $WHILE_ITERATOR -le $MAX_ITERATIONS ]
# __Add call to process checking script here.__
do
# Appending hashtags to progress bar string.
PROGRESS_BAR="["
HASHTAGS=$WHILE_ITERATOR
HASHTAGS_ITERATOR=0
while [ $HASHTAGS_ITERATOR -le $HASHTAGS ]
do
# Accounting for first pass through outer loop.
if [ $WHILE_ITERATOR -eq 0 ]; then
PROGRESS_BAR+=" #"
else
PROGRESS_BAR+="#"
fi
HASHTAGS_ITERATOR=$((HASHTAGS_ITERATOR+1))
done
# Appending trailing spaces to progress bar string.
SPACES=$((MAX_ITERATIONS-WHILE_ITERATOR-1))
SPACES_ITERATOR=0
while [ $SPACES_ITERATOR -le $SPACES ]
do
PROGRESS_BAR+=" "
SPACES_ITERATOR=$((SPACES_ITERATOR+1))
done
# Closing progress bar screen and adding return esc char.
PROGRESS_BAR+="]\r"
# Setting echo -n to run properly on Unix & Mac
if [ "`echo -n`" = "-n" ]; then
n=""
c="\c"
else
n="-n"
c=""
fi
# Print the progress bar without \n; reprints in place.
echo $n "$PROGRESS_BAR" $c
sleep 1
WHILE_ITERATOR=$((WHILE_ITERATOR+1))
done
# Print final iteration of progress bar string.
echo "$PROGRESS_BAR"