Cloning an SD card to another in Ubuntu using a single SD card reader

you could use dd and your harddrive. I will give an example:

For the backup (with your rasbian jessy sd card in the reader, but unmounted):

sudo dd if=/dev/mmcblk0 of=/home/bruni/backup.img

For the restore, after you have unmounted and replaced the sd card with a fresh one:

sudo dd bs=4M if=/home/bruni/backup.img of=/dev/mmcblk0

Of course you will first have to verify that mmcblk0 is your sd card (to do this compare the output of df -h before and after you insert the sd card) and replace bruni with your username.

I use the above for backing up my raspberry pi kodi installation.

PS: Neither copy nor rsync will lead to a bootable sd card, which is what you want.

This can be done on the Pi. Using Piclone the Raspberry Pi can back itself up to an SD.

Menu > Accessories > SD Card Copier

Select the SD the OS is running from in the top box and the backup card in the lower.