Explanation:
dd is a command-line utility for Unix and Unix-like operating systems whose primary purpose is to convert and copy files. dd can duplicate data across files, devices, partitions and volumes On Unix, device drivers for hardware (such as hard disks) and special device files (such as /dev/zero and /dev/random) appear in the file system just like normal files; dd can also read and/or write from/to these files, provided that function is implemented in their respective driver. As a result, dd can be used for tasks such as backing up the boot sector of a hard drive, and obtaining a fixed amount of random data. The dd program can also perform conversions on the data as it is copied, including byte order swapping and conversion to and from the ASCII and EBCDIC text encodings. An attempt to copy the entire disk using cp may omit the final block if it is of an unexpected length; whereas dd may succeed. The source and destination disks should have the same size.