Raspberry Pi SD card backup

piBak.sh

#!/usr/bin/env bash

#Sudo check
if (( $EUID != 0 )); then
    echo -e "\nPlease run as root or use sudo\n"
    exit
fi

# OS checks 
arch=$(uname -s)
case $arch in
  Darwin*)
    listDisk='diskutil list'
    ;;
  Linux*)
    listDisk='lsblk'
    ;;
  *)
    exit
    ;;
esac

# User instruction 
eval $listDisk
echo -e '\e[1;25;34mExample: disk2 or sdb2\e[0m\n'
read -p 'Disk to be copied?: ' diskVar 

# Main attraction
echo -e "\e[1;25;33m"
read -p 'Are you sure? [Y/n] ' response
case "${response:-y}" in
  y|Y )
    umount /dev/$diskVar* 2>/dev/null
    echo -e "\e[1;25;32m"
    # This because rdisk is amazing
    # Prefer ddrescue if available
    case $arch in
      Darwin*)
        if hash ddrescue 2>/dev/null; then
          ddrescue /dev/r$diskVar $HOME/Downloads/piBak`date +%m-%d-%y`.img
        else
          dd if=/dev/r$diskVar of=$HOME/Downloads/piBak`date +%m-%d-%y`.img bs=100M
        fi
        ;;
      Linux*)
        if hash ddrescue 2>/dev/null; then
          ddrescue /dev/$diskVar $HOME/Downloads/piBak`date +%m-%d-%y`.img
        else
          dd if=/dev/$diskVar of=$HOME/Downloads/piBak`date +%m-%d-%y`.img bs=100M
        fi
        ;;
    esac
    ;;
  n|N )
    echo 'Ok, maybe later.' ;;
esac