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After re-installing a Linux machine, I inadvertently ran wipefs -a on the installer pendrive:

$ wipefs -a /dev/sd? /dev/sda: 8 bytes were erased at offset 0x00010040 (btrfs): 5f 42 48 52 66 53 5f 4d /dev/sdb: 8 bytes were erased at offset 0x00010040 (btrfs): 5f 42 48 52 66 53 5f 4d ... /dev/sdw: 8 bytes were erased at offset 0x00010040 (btrfs): 5f 42 48 52 66 53 5f 4d /dev/sdx: 8 bytes were erased at offset 0x00010040 (btrfs): 5f 42 48 52 66 53 5f 4d /dev/sdy: 5 bytes were erased at offset 0x00008001 (iso9660): 43 44 30 30 31 /dev/sdy: 2 bytes were erased at offset 0x000001fe (dos): 55 aa /dev/sdy: 8 bytes were erased at offset 0x00000200 (gpt): 45 46 49 20 50 41 52 54 /dev/sdy: calling ioctl to re-read partition table: Success

As wipefs output contains the offset and the content of the deleted bytes, it seems possible to restore /dev/sdy. How would you do it?

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1 Answer 1

Reset to default
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First off, make a copy of the affected area of /dev/sdy before touching it again:

dd if=/dev/sdy bs=65536 count=1 of=sdy.back

Then, to restore the original data:

printf '\x55\xaa\x45\x46\x49\x20\x50\x41\x52\x54' | dd bs=1 seek=$((16#1fe)) of=/dev/sdy printf '\x43\x44\x30\x30\x31' | dd bs=1 seek=$((16#8001)) of=/dev/sdy

(adding sudo before dd if necessary). 0x200 immediately follows two bytes at 0x1FE, so the ten bytes can be written in one step.

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