How to create a backup image of your SD card while your Raspberry PI is running?

You can create a backup (.img) of your SD card to a network / USB drive while the card is inserted in your Raspberry PI!

• make sure you have access to your network drive / usb drive;
  to see the devices type:
  sudo cat /etc/fstab

• create an img of the card currently in the PI to your network drive / USB drive using the dd command:
  sudo dd if=/dev/mmcblk0p2 of=/home/pi/networkdrive/my.img bs=1M
  (replace /dev/mmcblk0p2 with your own SD card and /home/pi/networkdrive/my.img with your own network drive / USB drive + image file name)

Good luck!