Progress bar / Loading icon whilst creating an MD5 hash for a USB

I'm trying to create a progress bar or some sort of loading icon to show that a hash is being created, instead of a blank screen with nothing happening... This is what I have so far:

if [[ $hashing != "y" && $hashing != "Y" ]]; then
                        echo -e "\n"
                        sudo dd if=dev/"$source" | md5sum
                                read -r compareresult
                                        i=1
                                                sp="/-\|"
                                                echo -n ' '
                                                while true
                                                do
                                                        printf "\b${sp:i++%${#sp}:1}"
                                                done
                                        exit        
                    fi ;;

This uses a spinning wheel to represent a loading icon. And it does work using what's above. But doesn't at the moment? Not sure if the order is incorrect or if I'm missing something. Any help would be great thanks

#!/bin/bash
#Clone_Command
while true
    do
    sudo -s
    echo "==========================="
    echo "   Clone Command    "
    echo "==========================="
    echo -e "\n"
    
    echo -e "\n"
    
    echo "Enter 1 for source device"
    echo "Enter 'a' to hash source device"
    echo "Enter 2 for destination device"
    echo "Enter 3 to list all available disks"
    echo "Enter 4 to execute dd command"
    echo "Enter 5 to compare MD5 hashes"
    echo "Enter q to exit"
    echo -e "\n"
    echo "PLEASE NOTE LISTING ALL DISKS WILL REQUIRE YOU TO RELOAD THE SCRIPT"
    echo -e "\n"
    echo -e "Enter your choice \c"
    read -r choice
    case "$choice" in
        q) exit;;
        1) echo -e "Enter source device '/dev/---'
                
Enter the last 3 letters of the device eg - sdf or sdb etc"

            read -r source ;;
            
        a) echo -e "Hashing this device may take a while depending on size"
                echo -e "\n"
                echo -e "Press enter if you wish to hash this device"
                
                read -r hashing 
                
                        if [[ $hashing != "y" && $hashing != "Y" ]]; then
                        echo -e "\n"
                        sudo dd if=dev/"$source" | md5sum
                                read -r compareresult
                                        i=1
                                                sp="/-\|"
                                                echo -n ' '
                                                while true
                                                do
                                                        printf "\b${sp:i++%${#sp}:1}"
                                                done
                                        exit        
                    fi ;;
            
        2) echo -e "Enter destination device '/dev/---'
                
Enter the last 3 letters of the device eg - sdf or sdb etc"

            read -r destination ;;
            
        3) echo -e "Press enter to list all available disks \c"
            read -r answ
        if [[ $answ != "y" && $answ != "Y" ]]; then
        clear
        sudo lshw -class disk
        exit
        fi ;;
        
        4) echo -e "This will format $destination. If you wish to continue press enter \c"  
            read -r ans
        if [[ $ans != "y" && $ans != "Y" ]]; then
        echo -e "\n"
            sudo dd if=/dev/"$source" of=/dev/"$destination" bs=4096 status=progress
            exit
        fi ;;
        
        5) echo -e "If you wish to compare MD5 Hash of both USBs then press 'Enter'\c"
                read -r compare
        if [[ $compare != "y" && $compare != "Y" ]]; then
               echo -e "\n"
               echo -e "Please note this is not a quick process"
               echo -e "n"
               md5sum -c <<<"$compareresult  /dev/$destination"
        fi ;;
    esac
done            

Progress view with pv

There is a general problem with your concept because USB sticks have slightly different sizes even when the nominal size is the same, and that will affect the md5sum of the whole device.

• If you check the md5sum of each partition, you can check that the original one and the cloned copy are the same.
• An alternative is to store an image file and use the md5sum and the size of the image to apply on the sticks (checking with dd exactly the same number of bytes as in the image file).

Instead of a spinner you can use pv, progress view, for example

$ sudo pv /dev/sdc | md5sum
29,8GiB 0:13:46 [37,0MiB/s] [================================================>] 100%            
2372da0e77d754a912078af8e47b36c9  -
$ 

It can be better to check only the relevant partition(s),

$ lsblk -f /dev/sdc
NAME   FSTYPE      LABEL UUID                                 MOUNTPOINT
sdc                                                           
├─sdc1                                                        
├─sdc2 vfat              34D9-D113                            
├─sdc3 ext4              3c66d05d-bc02-4a1e-baca-e227a161e345 
└─sdc4 crypto_LUKS       371f0cbc-3f6f-49dd-9fc4-4cdf91cb15c9 

in this case partition #4,

$ sudo pv /dev/sdc4 | md5sum
1,66GiB 0:00:46 [36,2MiB/s] [================================================>] 100%            
35d33ae006c90b47b2e7b9aacb7f9bd7  -

Please remember to unmount the partitions on the USB stick before checking the md5sum.

Cloning a drive with a safety belt

You can clone from one USB stick to another stick (or card or SSD, any mass storage device) with mkusb-dus which also uses pv if installed and watch-flush to monitor the progress of the cloning operation. Assuming the source drive is sdx, run

dus /dev/sdx

It will help you identify the correct target drive (help you avoid overwriting the wrong drive), so you do not specify the target on the command line.