[ bash ] Create a ProgressBar function display

#!/bin/bash
# Create a ProgressBar function display
# loool video tutorial => http://youtu.be/msZpNZuhi6A


# Variable declarations
_start=1 # first state (start 1%)
_end=100 # final state (end 100%)


function ProgressBar {
    let _progress=(${1}*100/${2}*100)/100
    let _done=(${_progress}*4)/10
    let _left=40-$_done

      # Build progressbar string lengths
      _fill=$(printf "%${_done}s")
      _empty=$(printf "%${_left}s")

# Build progressbar strings and print the ProgressBar line
# Output example: [########################################] 100%
printf "\rProgress : [${_fill// /#}${_empty// /-}] ${_progress}%%"

}




# Proof of concept (loop)
for number in $(seq ${_start} ${_end})
do
    sleep 0.1
    ProgressBar ${number} ${_end}
done
printf '\nFinished!\n'