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How would i do a hexdump in Ubuntu for the first track of a HDD?

I am looking for a winhex-esque output if that makes sense. The first track has 63 sectors, each 512 bytes long. I tried

dd if=/dev/sda bs=1 count=512 | hexdump -C

but that only gave me what appears to be the MBR, or first sector of the HDD. I guess i am confused about what bs and count should be. Bs means how many bytes to display and count is how many multiples of bs? Thanks!

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If i try bs-1 count=32256, it appears to truncate the output to only about two pages worth of scrolling within the terminal... i have no idea why. – Daniel Gratz Jun 29 '11 at 15:32

bs is the block size, in bytes, and count is the number of those blocks to grab. So the command you actually want to dump the first track is:

dd if=/dev/sda bs=512 count=63 | hexdump -C

The dd man page might be of help.

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Thanks. Any idea why i'm not seeing the full output? I don't even see the 1st block (MBR) when i type the above command. It shows me output only between 000050d0 and 00007e00. – Daniel Gratz Jun 29 '11 at 15:34
Would hexdump -C -n 32256 /dev/sda not work? – RedGrittyBrick Jun 29 '11 at 16:13
Yes, you think that you're using an interactive hexediting program, as on Windows. You're using a non-interactive program that just dumps everything in one long stream of output, only the last N lines of which are left on your terminal at the end. The next Unix building block for you to learn is the more (or less) command. (-: – JdeBP Jun 29 '11 at 16:13
When I finish overwriting my USB stick, I can test this, but couldn't you try to dump it into a file to browse through. Wouldn't dd if=/dev/sda bs=512 count=63 | hexdump -C > firsttrack.txt output it to a file? – Rob Sep 13 '11 at 16:29

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