Use clonezilla to create a Ubuntu image and restore it on Mac Pro laptop

A better way is to use https://www.macrium.com/reflectfree

http://clonezilla.org/
Download the stable version and save the files to a USB.
Press Alt + Power button and choose EFI as the boot option.
Start Clonezilla and follow the on screen instructions. Basically I need another hard drive to save and restore the image.

Do the same thing so that the image can be restored on another computer.

!!!IMPORTANT!!!: the target partition size must not smaller than the original backup size.