Clone HDD or flash disks

The image created may be too large for your hard drive:
dd if=/dev/sda of=hdd.img

Clone the image back onto another drive:
dd if=hdd.img of=/dev/sda

MBR Total Size = 446 + 64 + 2 = 512

• 446 bytes - Bootstrap.
• 64 bytes - Partition table.
• 2 bytes - Signature.

512 vs 446 Bytes:

• Use 446 bytes to overwrite or restore your /dev/XYZ MBR boot code only with the contents of $mbr.backup.file.
• Use 512 bytes to overwrite or restore your /dev/XYZ the full MBR (which contains both boot code and the drive's partition table) with the contents of $mbr.backup.file.

dd command to copy MBR (identically sized partitions only)

Type dd command as follows:
dd if=/dev/sda of=/dev/sdb bs=512 count=1

Above command will copy 512 bytes (MBR) from sda to sdb disk. This will only work if both discs have identically sized partitions.

dd command for two discs with different size partitions

dd if=/dev/sda of=/tmp/mbrsda.bak bs=512 count=1

Now to restore the image to any sdb:
dd if=/tmp/mbrsda.bak of=/dev/sdb bs=446 count=1