Recipe: Cloning hard drive and disks with dd

SYNTAX:
$ dd if=SOURCE of=TARGET bs=BLOCK_SIZE count=COUNT

if stands for input file or input device path
of stands for target file or target device path
Total bytes copied = BLOCK_SIZE * COUNT

Copy a partition into a file
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# dd if=/dev/sda1 of=sda1_partition.img 
Here /dev/sda1 is the device path for the partition. 

Restore the partition later on using the backup image of the parition.
# dd if=sda1_partition.img of=/dev/sda1 


Clone one hard disk to another hard disk of same size
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# dd if=/dev/sda  of=/dev/sdb

# /dev/sdb ( Second hard disk)


Take image of a cdrom (ISO file)
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# dd if=/dev/cdrom of=cdrom.iso 


Mounting image files
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# mkdir /mnt/mount_point
# mount -o loop file.img /mnt/mount_point