Re: Default number of overwrites in shred

[HggdH]

On Thu, 2009-01-22 at 13:14 +0000, Pádraig Brady wrote:
> Jim Meyering wrote:
> > Sure.
> > Too many people waste too much time with the existing defaults.
> 
> Pushing the attached soon so.

A consequence of this change -- right now -- is that all 3 passes will
be random. I am not sure if this was the intended result or not.

The current pass select logic forces the first and last passes to be
random, and inserts a random pass (if there is not a big enough
selection) in the middle. End result is all passes are random.

But, indeed (and as far as a single run can be of any value), the
elapsed time did go significantly down.

Example runs:

address@hidden:/tmp $ shred --version
shred (GNU coreutils) 7.0.147-83ae1
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Written by Colin Plumb.
address@hidden:/tmp $ time shred --verbose -n 25 test.data
shred: test.data: pass 1/25 (random)...
shred: test.data: pass 2/25 (000000)...
shred: test.data: pass 3/25 (492492)...
shred: test.data: pass 4/25 (111111)...
shred: test.data: pass 5/25 (555555)...
shred: test.data: pass 6/25 (777777)...
shred: test.data: pass 7/25 (249249)...
shred: test.data: pass 8/25 (eeeeee)...
shred: test.data: pass 9/25 (db6db6)...
shred: test.data: pass 10/25 (aaaaaa)...
shred: test.data: pass 11/25 (b6db6d)...
shred: test.data: pass 12/25 (ffffff)...
shred: test.data: pass 13/25 (random)...
shred: test.data: pass 14/25 (bbbbbb)...
shred: test.data: pass 15/25 (6db6db)...
shred: test.data: pass 16/25 (cccccc)...
shred: test.data: pass 17/25 (dddddd)...
shred: test.data: pass 18/25 (999999)...
shred: test.data: pass 19/25 (444444)...
shred: test.data: pass 20/25 (666666)...
shred: test.data: pass 21/25 (924924)...
shred: test.data: pass 22/25 (888888)...
shred: test.data: pass 23/25 (333333)...
shred: test.data: pass 24/25 (222222)...
shred: test.data: pass 25/25 (random)...

real    0m22.306s
user    0m0.056s
sys     0m11.601s
address@hidden:/tmp $ time shred --verbose test.data
shred: test.data: pass 1/3 (random)...
shred: test.data: pass 2/3 (random)...
shred: test.data: pass 3/3 (random)...

real    0m8.985s
user    0m0.020s
sys     0m8.185s
address@hidden:/tmp $ ls -l test.data
-rw-r--r-- 1 hggdh hggdh 11280384 2009-01-23 14:32 test.data
address@hidden:/tmp $ 


Regards,

..hggdh..

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