loop_progress_bar.sh

#!/bin/bash

function progress_bar() {
  if [ $1 -eq 0 ];then
    comp_p=0
  else
    COMPLETED=$(($COMPLETED+$STEPS))
    comp_p=$(jq -n $1/$ITEM_COUNT*100)
    comp_p=$(echo ${comp_p%.*})
  fi
  x=$(perl -E "say '=' x $COMPLETED")
  echo -ne "  |" $x" | $comp_p%\r"
}

function loader_init() {
  ITEM_COUNT=$1
  STEPS=$((100/$ITEM_COUNT))
  COMPLETED=0
}

# copy and paste above functions and use it inside a loop as shown below

# pass number of items
loader_init 10
progress_bar 0

for i in $(seq 1 $ITEM_COUNT)
do
  # do stuffs here
  sleep 0.2
  progress_bar $i
done

echo