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Did you know that when you
delete a file or directory you are not deleting the data
itself but merely the pointers that the file system
maintains to the data?
Also, did you know that there are a number of ways to
recover deleted data including freeware utilities, paid
utilities and even professional services?
Sometimes you want to be able
to recover files deleted accidentally, but sometimes you
never want a file to be seen again. Examples of situations
when you might not want a file(s) seen again is when you
give an old computer away or leave a job.
You may, for example, want to
delete financial records, private correspondence, emails,
spreadsheets, document files, personal pictures and videos,
and more. Anything that may contain sensitive information or
material you would not like the world to be able to see.
Just like there are programs
available to recover data, there are programs available to
make sure your deleted files are not recoverable.
One of those free tools that
works from the command prompt and can be automated is
SDelete by Mark Russinovich available for free from the
Sysinternals web site.
SDelete
- Secure Delete v1.4
Copyright (C) 1999-2005 Mark Russinovich
Sysinternals - www.sysinternals.com
usage: sdelete [-p passes] [-s] [-q] <file or
directory>
sdelete [-p passes]
-z [drive letter]
-p passes Specifies number of overwrite passes (default is 1)
-s Recurse subdirectories
-q Don't print errors (Quiet)
-z Clean free space |
You can visit the SDelete
page to read the technical details on how it works. Here I
will present two short batch files showing how you might use
it.
What I will illustrate here
is how to use SDelete to make all the currently deleted data
on your drives unrecoverable.
The first method is to use a
for loop that specifies exactly which drives to 'clean' the
data from. In the example below I am cleaning drives C, D,
E, F & I.
I am using a single pass.
(See the SDelete web page.) To change the number of passes
simply increase the number after -p to the number of passes
you want to use. (You can also run this directly from the
command prompt by replacing the %%s with a single %.)
| for %%c in (c d
e f i) do @sdelete -p 1 -z %%c: |
It's a very simple batch
file but one that can save you much embarrassment or
even prevent identity theft in some circumstances. You
might want to run it manually or schedule it from a the
task scheduler every once in a while, daily, weekly,
monthly, as you prefer, perhaps overnight when your
computer is turned on but not in use.
The batch script below
will check every possible drive letter and clean each
drive that exists. You should keep in mind that you may
have external disks mounted and should use this with
version when that is not an issue.
for
%%c in (C D E F G H I J K L M N O P Q R S T
U V W X Y Z) do (
if EXIST %%c:\NUL (
@sdelete -p 1 -z %%c:
)
) |
You will need to run
these scripts from an account with administrative
privileges.
SDelete
is currently available here,
http://www.sysinternals.com/Utilities/SDelete.html
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