How to backup Raspbian SD card into your harddisk

To backup, you cannot directly copy Raspbian files into your hard disk. What you need to do is create a disk image. Disk image will preserve all the files and filesystem structure of the SD Card regardless of what desktop OS you use.

On Ubuntu or other Linux system type the following command:

dd if=/dev/sdx of=/path/to/image bs=1M

Where /dev/sdx is your SD card.

For example I want to copy my Raspbian installation from SD card into my external harddisk attached to my laptop I use the following command:

dd if=/dev/mmcblk0 of=/media/SAMSUNG/raspbian.img bs=1M

To copy it back onto the card or any other card, you can use flashing application such as ImageWriter, just like how you would install your Raspbian OS for the first time.

Good luck!