dd

Most of Windows users may know "Norton Ghost". Norton Ghost is a backup software for hard disks. It can backup a whole hard disk or a partition to an image file. Also, Norton Ghost can copy all the contents from a hard disk to another exactly. However, Norton Ghost is a Windows software, users on other operating system (such as Linux) can not enjoy its powerful function. Fortunately, most of Unix/Linux operating system provides a command line whose function is similar to Norton Ghost, it is called "dd".