Duplicate one hard disk partition to another hard disk

Using dd to duplicate one hard disk partition to another hard disk:

dd if=/dev/sda2 of=/dev/sdb2 bs=4096 conv=notrunc,noerror

Replace /dev/sda2 and /dev/sdb2 with your partitios.
Note that notrunc means do not truncate the output file. Noerror means to keep going if there is an error.