I was able to create a ext3 partition with out any problems using Gparted and now I am trying to send over a persistence.conf but it fails each time, here is what commands I am running:
sudo mkdir /mnt/usb
sudo mount /dev/sdb3 /mnt/usb
sudo echo "/ union" >> /mnt/usb/persistence.conf
bash: /mnt/usb/persistence.conf: Permission denied
Does anyone know how to fix this?