Erasing files in Ubuntu: other devices still see the files

Dotan Cohen dotancohen at
Sun Feb 10 21:35:27 UTC 2008

On 10/02/2008, NoOp <glgxg at> wrote:
> On 02/10/2008 06:12 AM, Nikhil Nadig A wrote:
>  >
>  > Hi Dotan,
>  >
>  > Try sudo shred -v -n 1 /dev/sdb1 (assuming your memory stick to be
>  > detected as sdb)
> I believe that command (-n 1) causes shred to overwrite the file 1 times
>  instead of the default 25 times. Further it you want the files to be
>  truncated and removed after overwriting you should use the 'u' option:
>  shred -u <filename or filenames - wildcards work also>
>  man shred:
>   -n, --iterations=N
>               Overwrite N times instead of the default (25)
>    -u, --remove
>               truncate and remove file after overwriting
>  Delete FILE(s) if --remove (-u) is specified.  The default  is  not  to
>  remove  the  files because it is common to operate on device files like
>  /dev/hda, and those files usually should not be removed.  When  operat‐
>  ing on regular files, most people use the --remove option.

Thanks. I did not even think that the problem was that the files were
not shredded. So there is a bug in the DVD player, that it shows files
marked as deleted. That just goes to show how easy it is to
'accidentally' find files that were simply deleted.

I will start using shred on sensitive data. Thanks, this was a really
good lesson in security.

Dotan Cohen

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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