Question

Using dd commands (linux) and its variations, given a usb, how would you:

1.) Create a bit-wise image called image.dd

2.) Create a bit-wise image called image.dd with sha1 hash

Answer 1

Answer 1
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Syntax
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dd if=/dev/input/DEVICE-HERE of=/dev/OUTPUT/DEVICE-HERE bs=64K conv=noerror,sync

where

1) if=/dev/file : Input device/file.
2) of=/dev/file : Output device/file.
3) bs=64k : Sets the block size to 64k. You can use 128k or any other value.
4) conv=noerror : Tell dd to continue operation, ignoring all read errors.
5) sync : Add input blocks with zeroes if there were any read errors, so data offsets stay in sync.

first find the usb drive using following command
sudo lsblk

find device path, LABEL, UUID and TYPE of block devices with help of command
sudo blkid

# sudo dd if=/dev/sda of=/home/madhav/Desktop/image.dd bs=64K conv=noerror,sync

above is my home desktop path of madhav username
Answer 2
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sha1sum {file}

# sha1sum image.dd

above command will generate sha1 sum for the file

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