Rsync a folder to two drives at the same time

camera-disk-rsync.sh

#!/bin/bash

if [ $# -lt 4 ];
then
    echo "Usage: camera-disk-rsync.sh DESTINATIONFOLDER MOUNT1 MOUNT2 SOURCEFILE\r\n"
    echo "Where MOUNT1 and MOUNT2 are the mountpoints of the two drives"
    exit
fi

foldername=$1
mount1=$2
mount2=$3

shift
shift
shift 
mkdir -p $mount1/$foldername
mkdir -p $mount2/$foldername

rsync -av --prune-empty-dirs "$@" $mount1/$foldername &
rsync -av --progress --prune-empty-dirs "$@" $mount2/$foldername